Things to look for or avoid in camper-back trucks?

Planning on eventually grabbing a Pickup with a camper-back on it, any specifics I should look for, accesory brands to avoid (or replace asap). What are things you wish you had known prior to purchasing one?
Models known for having issues with things like poor insulation or faulty heaters, etc.

The goal is travel up and down the coastlines, east & west once I get hvac certified and eventually finding an ecovillage to settle in.

 

https://www.youtube.com/watch?v=_kAR5mY6PGk"]Cricket Trailer Two - YouTube

 

do it the old hippy way with a 1969 volkwagen camper bus, that how i want to

 

I had one, not well enough insulated in winter months and I dont want to have to relocate just because of weather. It was great during Spring summer and fall but Winter wasn't so much fun.

 

Heres a neat option I've toyed with for a lil' while,

http://www.glen-l.com/campers/campers.html

At least if it weren't insulated well enough I'd only have myself to blame.

 

I've seen several of those campers for sale in the Atlanta area for 2500.00 or so (older but good shape) Don't know much about them