1) Do I really need a dually? No, if you stay below 14,000lbs loaded, AND your pin weight is within the truck's specs.
2) Will I need a one ton truck or will a 3/4 ton work? You need a one ton, and the newer the better, because of engine and transmission improvements.
3) Can I use a swb, or will I need a lwb? A short bed will likely require a sliding hitch. A manual slider is okay but I'll guarantee there will come a time when you forget to get out and manually slide. Factor in extra cost for an auto slider or repairs to your truck and fiver.
4) Generator. Some FWs are prewired for gensets. OTOH, adding a genset in the front basement adds significantly to pin weight. If you're going to do a lot of boondocking you will need one. I suggest an inexpensive Champion 3400, or other brand, which is adequate to run one 15k AC, and recharge your batteries in the AM.