You just opened another can of worms... sorry ahead of time but this is probably a real good exercise for me in planning my camper...
say you had the opportunity to buy a new camper knowing what you know now what 'special framing' and 'special wiring' would be most critical for future upgrades. I know a lot of it depends on how you camp and what you want to do with the camper, I tend to tweak nearly everything i own to make it work better or simply more comfortable to live out of. Granted i've never owned a camper so i'm speculating a bit on what features would work best for us, as i mentioned above a simple shell with room to mod would be a huge upgrade for us, but i'm sure as time would go on cool features would be needed and i'd like to set it up for those. We camp, hunt, ski, explore and i can see this thing getting used alot long weekends to week long trips, fall hunting early mornings and late nights, wet and cold conditions with the need to dry gear and dogs
lighting indoor and outdoor
-reading in bed
-living area
-cooking under an awning
-backup lights
-area light late night peeing, working on stuff at night, early morning prep
-etc
power
-batteries, it seems lots of folks are upgrading to on board power and solar charging, great but expensive idea
-wiring for outlets
-ideally in the future i could have enough on board power to camp for a week without the truck, dual batteries charger, solar panel
water
-don't think i want a sink and h2o storage, but last night i look at my water jugs and thought maybe it won't be a bad thing to have?? can you plumb the thing after the fact, i know you can do most anything but is it a real pain
fridge/freezer
-again looked at the coolers and said it'd be sweet to have an on board freezer,
-3way or 2 way, run it off the truck while drive and propane while camping? again i should have the wiring run
Converters?
Awning
-cooking and drinking and beer in the shade or out of the rain, nice concept
-plan is to cook outside unless its damn cold than of course, we've hunted out of wall tents for years and it's damn nice to have the stove inside for early morning coffee and breakfast
racks
-should the roof have extra support?
again sorry for the rant but the more i think about it the more this thing is costing me!