The gvwr mentioned above not being a legal value only liability for the manufacturer and warranty may be true, but your insurance can deny a claim if they determine you were over the gvwr as its not just what the vehicle can carry, but also whether the vehicle can stop and maneuver safely. The highway patrol can also pull you over if looks like you're over the weight limit.
(Let's not get into whether the police should or should not in this discussion please)
Many people do carry something like a four wheel camper shell model hawk which says 1,100lbs dry, so that doesn't include water, frig, heater, solar, battery etc.
Also the 1,850 payload capacity you mention is misleading, as it is on ALL trucks. That is TOTAL payload including passengers, fuel, and whatever else you might carry in the cab portion.
If there are two people at 150 each then that 1,850 capacity has already dropped to 1,550.
If you're looking for something light as a semi permanent popup you might try
https://campovrlnd.com/products/ovrlnd-pop-top-camper they start at around $8,400. and around 300lbs.
I'm building my own and plan to keep the weight as light as possible.