I've known these kinds of builds as truck [campers, shells, toppers] and such, and there are loads of specialized forums that you want to find and ask your questions in. Some specific to 4-wheeling, and others to stealth-camping, off-the-beaten path camping, etc. Those forums and folks really have the
experience. The top of the line experience is an "earthroamer" (be sitting down for the price tag) ... and then there's my budget range ... a Leer Topper, for a few bucks.
Some sites that I have found useful are:
https://www.cheaprvliving.com/
https://www.expeditionportal.com/
But there are tons more ...
Here's a site and a specific topic about wood vs aluminum (link still works ... amazing):
http://www.truckcamperadventure.com/2017/02/why-wood-frame-construction/
A real specific consideration for you might be ... are you still 4wd'ing, off the beaten path, every weekend? If that kind of driving, you'll want to pay close attention to what you build out, and the forums will help you figure it out.
We now just "get off the beaten path" to primitive areas, so we could've built a full truck camper on the back ... the truck and camper would survive getting way out there (no state parks & asphalt roads or campsites, more national forests & BLM 4wd driving for primitive sites). The camper would've survived our earlier 4wd days, but it would've looked like a dent clearance-sale item, what with tree branch clearance and other tight situations from that kind of 4wd'ing.
I've waffled a bunch with building out a camper or a topper, and when I found just the right high head-clearance leer topper (for a song, almost) for the back of my F350 8' truck bed, things have been moving towards a topper buildout for us. This should survive our kind of 4wd'ing these days. It's got a pass-thru
boot to the 4-door cab, so we can pass back and forth (if raining or such). A high-topper on an 8' bed has tons of room to build in, so this topper and the truck should accommodate up to 4 of us on BLM or other such boon-docking, middle of nowhere trips.