What a great summer you've got in store. It's awesome you've got the spirit of adventure to do it.
I do a 2-3000 mile road trip in the west every summer. These old trucks can be just as dependable as anything, but it's a big advantage to know your truck. What I mean by that is that if there's a problem you can almost guess what it is before you pop the hood. If you've had your truck long you probably know what systems are iffy and whats good-to-go. If you know you've got a leaky diff, fix it or at least carry extra gear oil and check it often enough.
Here's a story if I may:
I stopped on the side of the road once in SE Oregon to take this photo.
When I got back in the truck it had a hesitation when it started and my girlfriend gave me a oh S*** look, and said "
well that don't sound good". 100 miles later we stopped for a break and got my tarp from behind the seat to have a look at starter and alternator connections. It ended up being a bit of corrosion under the negative battery post. No big deal, but I needed a 1/2" wrench and a little wire brush. My point is that these are pretty simple mechanical machines and most problems can be dealt with, as long as you can keep your cool and think things through. Although, it's a bit distracting when your truck wont start and your 100 miles from a town.
Behind the seat I always carry a shoe box full of everything electrical including a test light, a duffle bag full of hand tools, and a fire extinguisher within easy reach. Try to think about things that'll leave you sitting on the side of the road and prioritize from there. In the back I carry a military rocket box (cause it's waterproof) with spare fuel pump, alternator, coveralls, tarp, Chilton manual, belts, hoses, vacuum hoses, and about 20 pounds of spare bolts/nuts/washers. Especially the weird one's that you'll never find when you need them. I also carry a milk crate with spare fluids. A smart phone is pretty handy too (when there's a signal) to find the nearest Napa, or junkyard.
A lot of the ranches in the west still have old squares that're working, rain or shine. You and your truck will fit right in.
Sorry this is a bit long. Keep us posted on your adventure.
Good luck, Mick