I have a one-ton truck and slide in camper. I keep the spare tire in its original storage location under the bed. I am not concerned about theft of the spare tire (touch wood). In fact, I removed the spare tire lock and key (Ford) so that I do not need to worry about it if I ever need to lower the spare. If someone wants my spare tire badly enough that they want to go through the PITA process of getting it out, I applaud them and they can have my tire.
My spare tire is stock, but the four tires on my wheels are larger than stock. I bought the truck this way. If I ever need to put the spare on, I can only put it on one of the front wheels since it is smaller than the stock wheels (so as not to destroy the rear axle), and then I could only limp at a very slow speed. I cannot replace the spare with the same, larger size tire as the four on the wheels because it wouldn't fit. The four tires are very good and practically new, so I am not replacing them with stock tires for now.
I am not interested in carrying a spare anywhere else. I do not want to block the front of my truck, there is no room in my truck's cab, there is no room on the roof, and there is no room on the back.
I have a good, solid jack that I know how to use safely. That is necessary because the truck and camper combo is very heavy, and I am not as well-serviced by the jack that came with the truck. I have a tire repair kit, too, but I can tell you that I hope to never use it. Plugging even a thin, compact car tire can be a bear, never mind a massive, thick, heavy-treaded 18" AT E-rated truck tire. And as someone mentioned above, that's only for holes punched in the treads, not the sidewalls.
Bottom line is that I want to avoid flats and blowouts, so I am careful about where I am driving, and I am fastidious about checking/maintaining tire pressure (I have good gauges and an air compressor onboard). If I ever get a flat, I will definitely first try to reach roadside assistance (I have two separate services). My tire repair kit and spare are truly for emergencies only when I absolutely need to move away from my current location and have absolutely no way to reach roadside assistance. For me, that's a PITA operation that involves jacking up a very heavy vehicle, possibly under iffy circumstances (unstable/uneven ground, sand, etc.), possibly in the dark, etc. I am lazy and not mechanically-inclined, so I'll avoid that scenario if at all possible. I can do it, but it would not be pleasant or easy.