Mom,
You might as well get a stiffer, heavier anti-sway bar too with that much weight. Have every known weak part on your truck replaced with stronger aftermarket parts. Tires make a big difference. If you are staying on pavement, go to 19.5's for shear capacity, but don't expect to cruise beach sand as they do not deflate well. You didn't mention 2WD or 4WD. This also makes a difference in payload, the 4WD having less. The '99-'02 or so has the best reputation, as the most reliable of the International Harvester engines in a Ford. With a heavy load and older tech (pre Diesel Warz), you will be slowing down on the hills. I was going to ask if you had a pre-DEF and soot bag, smog controlled truck (2006 being the cutoff year), but you answered my query. You should be good to go with Mexican and Central American diesel fuel with judicious filtering. If you have an automatic transmission and it has a small oil cooler, get a bigger trans cooler. Your C-4 or C-6 is a good trannie (assuming you have one) but the achiles heel of ANY auto trans is heat.
The Rule of Thumb (whoever invented that term?) is, "the longer you are out on the road in a truck camper, the larger and more comfortable you want the mobile domicile to be." We have the special privilege of having several full-timers on this forum with widely contrasting styles and modus operandi. There are a few good-to-haves: A BIG truck: 450/4500 and 550/5500 being the gold standard. What this means for you is you may want to have a lighter (smaller) camper to haul around, well below the GVW rating to fit your truck. There are scores of people on here that can guide you through the potential mine field of full timing preparation. Then again, one school of thought says: "just get in and go. You can work the bugs out along the way." There is no fix like a road fix. Digest as much info as you can (like the Vagabonds) before you write the check for a TC. No one but you knows the edges of your wants and needs as a full timer. If you are adept at writing, keep a blog. I'll be there in spirit.
jefe
'01.5 Dodge 2500 4x4, CTD, Qcab, SB, NV5600, 241HD, 4.10's, Dana 70/TruTrac; Dana 80/ TruTrac, Spintec hub conversion, H.D. susp, 315/75R16's on 7.5" and 10" wide steel wheels, Vulcan big line, Warn M15K winch '98 Lance Lite 165s, 8' 6" X-cab, 200w Solar