First and only camper was 2nd hand, as I didn't like the look of the new stuff in my price <$15k). The camper has been zero dramas at all, it's extremely well made and should stay that way for a long time.
First 4wd was also 2nd hand (2002 Pajero), again because we had a limited budget. The car had had a tough life before we got it and it needed a fair bit of money spent repairing things and keeping it going. In hindsight, I probably should have got a loan and bought something newer, with low kms, as I've easily spent the purchase price again on the "bargain".
We've recently bought a new 4wd, but I'm keeping the Pajero as a runabout as it's so nice to drive and it's well setup. A new 4wd is probably more useful due to the warranty and reliability etc etc. With a camper, there's not much that goes wrong, so buying brand new isn't so critical IMHO.