Welcome! Post up some pics of the new ride and some specs. That will help us to point you in the right direction.
As for long trips the number one priority is reliability so I'd suggest keeping modifications to a minimum, especially to important stuff like the suspension. I'd highly suggest spending the money on maintenance and baselining the truck. It's probably been somewhat neglected like many older trucks, so it would benefit greatly from some TLC. It's not as fun as mods, but it's way more important.
Honestly, I would be looking into the timing belt job (a biggie) if it hasn't been done and shoring up any leaks it may have. I'd also replace the shifter bushing with the white one from Marlin Crawler, which should ensure against shifting issues. I would also replace the diff, tranny, and transfer case gear oils, and ensure you grease all the zerks (there are like 14 of them) and slip yokes on both drive shafts. I would also look into possibly flushing the coolant (though this will likely be done if you do the timing belt) just to make sure it's fresh and happy. If it currently wanders or doesn't feel like the handling is tight, I would replace the shocks, the sway bar bushings and end links, and the steering damper, and then rebuild the idler arm. There are threads on here for all of these items with pics and part numbers. I would also inspect your clutch pedal bracket to make sure it's shiny black, and not grey. The grey ones crack and fail making shifting difficult or impossible. Also, make sure the firewall at the clutch master is solid and not deformed/cracked if you have the grey bracket. If you have the grey one, replace the assembly with the newer black version (again, in the name of reliability).
Less fun jobs include new pads/rotors if they are getting worn, checking/replacing ball joints of they are worn, and re-packing the front wheel bearings (a good idea if you do the front brakes at the same time).
You may also want to look into the battery...all the mods in the world won't help if the truck won't start!

This is especially true if you add lights. If you're on a budget, I'd skip the light bar all together and throw some generic off-road lights on there if you feel you need them. Just make sure you wire them through a relay...NOT directly through the cab switch (fire hazard).
And then I would look into tires, as these T100s sit very high. I don't think a lift would be needed, and may decrease reliability. Good tires and a reliability will get you *way* farther than you might realize. These trucks are great off-road stock. Grab some good 31" Ats and you should be good.
Make sure the rear axle isn't cracked near the spring perches...it's a failure spot on some of these.
Otherwise, I'd spend some money on a nice used shell so you don't have to cram everything in the bed, and get some good recovery gear in case you get stuck.