IMO a 2500 3/4 ton is the minimum. Yes the 1500 is too light in frame, shocks, all the stuff needed to carry you and your stuff safely.
All things equal- miles, condition, price (ha) I’d want the 3500, 1 ton for the extra safety and flexibility.
Weigh all the wood, insulation, solar, extra batteries, food, water (8lbs a gallon) fuels, stove, pots, pans, chairs, clothes, boots, shoes, computer toys, bedding, tools, you!, the dog and you’ll quickly see you can max out a 2500.
An under strengthened vehicle will breakdown (bend, sag, break) from the excess weigh. An over weight vehicle will stop much slower and may not stop at all.
Did you see the terrible story and video of the RV that could not stop when trying to load on a ferry? I don’t know the finally conclusion if it was ‘just’ bad brakes or the RV overloaded caused the brakes to fail resulting in a horrifying death for the man inside.
Don’t go light or cheap on the vehicle capacity, brakes, shocks, quality of tires