80 Series cruisers are fairly common, I imagine finding parts if you need them, should be easy enough.
I can offer a little advise after spending lots of time down there.
Chrome, or anything fancy is a bad idea; the uglier the better. It is not unsafe in Latin America, per se, but anything you can do to be less visible as a couple of gringos in a nice truck will help. Dents, dirt, rust offer some camouflage.
Camping is tough in Central America, there is not much wilderness. Even hiking will pretty much take you village to farm to village, I was very surprised how inhabited everything was in C.A. The further out spaces will put you at risk of robbery. Hostels and private property are the way to go. I would absolutely use a pay lot whenever leaving the vehicle overnight; even for short term parking in places like Guatemala City, Caracas, etc... they usually are fenced/attended and secure in my experience.
A 2nd spare isn't necessary, save the space- but plugs/compressor are. Be prepared to repair.
Water is always an issue. When I could, I would use the ceramic filter that many locals use and fill up. Usually it was just easier to buy clean water. UV purification would have been nice.
Be prepared for long border crossings. Plan on unloading everything for inspections. Speaking Spanish will go a long way with cutting through the corruption and getting on your way. I can't emphasize this enough. Know what you need ahead of time; cash (exchange rates)/photocopies/signatures/etc. Border officers will often try to tell you some BS like: "you need to go back 50km to get this and come back on Monday when so and so is here... or, you can just pay us 500 cordoba now. When they know you can communicate, they will fold.
Sounds like you're an experienced traveler, so I'm sure you're used to all the common sense stuff. I don't mean to sound like Latinos aren't trustworthy or to make you paranoid but many people are poor and honestly, to them you are wealthy. I can't tell you though, how many times I was blessed with compassion and hospitality. Once I bridged the communication barrier, a whole new experience opened up.
best of luck-
josh