A couple of points to add to my above post and perhaps to address some comments that followed.
Weight will always be the enemy. It puts a strain on all the mechanical parts, it limits where you can go, it's harder on engine, gas mileage, brakes, suspension, frame, etc. Things wear out faster. But that applies to all vehicles. Most of us have seen full size pickups which were overloaded with large campers, with bikes, canoes, power generators, winches, spare wheels, etc. (Same same, but different (bigger)).
All Terrain Campers (perhaps others as well) will happily build you a lightweight "shell" model of any of their campers. That's how mine started at 521 lbs. It came with a full sized 75 x 65" bed, a 4" foam mattress, I could stand up without slouching (I'm just over 6', or was last time I was last measured... I may have shrunk since then), it had insulated and finished walls, a finished floor, 4 windows, a roof vent, interior and exterior LED lighting, etc. It was hand made by professionals who have been building them for over 40 years and understand what is needed.
The Leer fibreglass truck bed topper that I had on the Tacoma previous to that weighed just over 300 lbs.
. Without any added comforts. It was a fibreglass shell with windows on the sides and the tailgate. I needed to crouch to get in and out. I needed to add a sleep system. etc. It was not weather sealed so when it rained water would seep in. No insulation. At the end of a long day on dry dusty roads, I'd open up the back to find a film of dust over everything. It got old very quickly. I was not comfortable. Cooped up inside for a day or two in the pouring rain made me an even less pleasant person to be around. And I'm a guy that lived and travelled out of a motorcycle for 9 months.
The best thing, I think, you can do is talk to as many people as possible who have a setup similar to what you are considering. I've had conversations with all manner of people in Walmart parking lots, rest stops, camp grounds, events, etc. asking them about their campers. I've approached some, some have approached me. Most people are happy to answer your questions if you come to them wanting to learn. Non-pro Tip: Ask them what they'd changed. There is no perfect system for everyone. We all have different wants and comfort tolerances. Listen to their answers. You might get some insight into what is important for them.
At last year's RTR I saw some wonderful builds of all shapes and sizes and talked with many who were happy to share their experiences. If you can make it down, it's a wonderful place to meet and talk to like minded people with similar and different builds. You should come away with a wide appreciation for what is possible. Ordinary people at events like the RTR are happy to answer questions and share experiences. I'm a veteran traveller (meaning both old and I have many miles under me) in all manner of vehicles and am anxious to go back and learn more.
I know I'm going off the OP's question here for a bit. Please bear with me.
Re the (not) 1/2 ton Tacoma. I have had the benefit of driving other people's Toyota Hilux pickups in Thailand, Argentina, and Costa Rica. They are vastly different from the Toyota Tacomas, which are exclusive to North American. Much of Toyota's reputation with pickups was made with the old Hilux that was available here until 1995 (I think?) and overseas where it is and was used in war zones, by farmers, etc... (Sidenote, the US military had long switched to the Ford Ranger prior to exiting Afghanistan) And as someone previously stated above, the 22RE 2.4L 4 cyl, was a fantastic little engine that could. But that has not been available in North America for a while now.
The current Toyota Hilux pickups are not simply rebadged Tacomas, or visa-versa. When Toyota first released the Tacoma in 1995 (I think?), they understood that North American farmers and businesses preferred a larger pickup. They understood the NA consumer market wanted a reliable, softer sprung, more comfortable, grocery getter. And while Toyota continued to develop and sell their Hilux work horses around the world, they traded that for comfort and connivance for the NA markets. And for that, for our big multilane highways, for taking the kids safely and reliably to school every weekday morning, for the occasional weekend camping venture with the girlfriend, they are a good choice, (if you can stomach the looks of the current model, but that's a personal taste).
Incidentally, the comparison reviews, all rate (including Consumer Reports) the current Ford Ranger above the current Tacoma.
I'm brand agnostic. I've owned Hondas, Toyotas, Subarus, BMWs, Mazdas. I've driven Dodges, Chevys, and Fords (legally) harder and faster than anyone should. I've ridden a 1200cc motorcycle from the east coast of Canada to the southern tip of South America, and then back in 9 months. I've flown to Vietnam, purchased for $300 a dodgy 110cc Honda Cub and road around that wonderful country. And now that I'm old(er), while I am still able, I want to go explore more of the world, for as long and as far as I am able.
So, after all my experiences, why did I pick a second Tacoma? I made a mistake. I had narrowed my choices down to the current Ford Ranger and a 1st generation Tacoma. I chose the first generation Taco as it is close enough to the old Hilux in design that I figured could probably find and fit parts as needed wherever and whenever I broke down. That, and also after an electronics problem I had with the motorcycle I rode to South America, I had placed too much emphasis on wanting as few electronics as possible controlling vital systems. Being able to fix mechanical issues when (not if) and wherever I happened to break down becomes important with international vehicle-dependant travel. That should not be a concern for most, unless you plan on venturing beyond North America (CDN, US, MX, and central America). I'm telling you all this as I don't want you to make the same mistakes I made. I should have chosen the current Ford Ranger, which is available around the world (Manufactured in Thailand, South Africa, Detroit, and I think somewhere in South America).
But don't listen to me. I'm just Joe Public. An old bloke. Don't follow my suggestions. Go out and make your own mistakes. If you are not afraid to make mistakes, you'll learn a lot. With that said, I'll share my non-professional opinion, I would not hesitate to put a well build, solid, lightweight camper on a small pickup with a minimum of 1200 lbs carrying capacity. Weight is your enemy. Bigger is seldom better, unless you don't want to go very far or off road. As others have pointed out, don't forget to factor in the weight of passengers, gear, food, fuel, water, spares, etc. Also consider what, where and how you plan to use your rig.
YMMV.
I hope you are all well! ✌
Santé,
Robert