Don't be scared, just be careful.
A while back I did start a thread in the CUCV section about electrical stuff, I never did have time to finish that, and I probably should - one section was supposed to be about charging batteries (like an auxiliary bank). If you can avoid adding more than you need you'll be better off, less to fail, less to repair, easier to trouble shoot, less impact on the original vehicle's operation...
Electric compressors in DC are not great - they aren't intended for high duty cycle (run-time versus rest-time, most retail ones are 20% run-time or less). AC compressors are better for higher-duty cycles - but I think you'd want to plan what you're going to do with it, figure out what's practical and work from there.
For my Fake CUCV Crew Cab build, I'm designing around having the truck power a camp and a "radio shack", so the first concern is fuel capacity, then power generation. If you're planning to do a lot of dry camping with your truck, you'll want to start by reducing and eliminating as many loads as possible. LED fixtures sip power, and are getting ridiculously cheap nowadays - focusing on task-lighting rather than full-space lighting with reduce the amount of light you have to produce and the power the lights consume. I'm sure you know that passive ventilation (windows/vents) is more efficient than powered ventilation - if you can handle being a bit warm with a good breeze versus being air conditioned then you can save a ton of power. If you're stationary, the benefits of having a shade canopy over your campsite are huge.
I can't find a link for it now, but to save wear on your "driving engine" another person built their own DC generator by using a small single cylinder engine powering a belt-driven alternator. If you have the space this can be a good way to make up what your solar array can't do, and if you have a spare York around, you can run it off the same engine to get air. If it's an air cooled engine, you can run copper coils through a few fins and pick up hot water when the engine is running. Try to maximize what you can pull out of the fuel being burned. A separate pull-start engine and alternator like that would also give you options for self rescue should you drain a battery in the engine compartment standing you in the middle of no-where with no cell signal.
You mentioned a "topper" is this a roof-top pop-up tent? If so, which one did you go with? Pics?