Welcome
And yes the people on here are very helpful.
I'm currently helping a mate look for a second hand Aussie manufactured camper as well, between the $10k-$15k mark. Have looked a few and all need a few more $K sunk into them before we'd take it on any trip.
The things we mainly check and in daylight.
Receipts for anything the owner has replaced either by a professional or by themselves.
Suspension and chassis cracking
Suspension brackets for cracking
Leaking Shocks, push on the camper multiple times in case the shocks have been cleaned
Rims for cracking and warping
Shake the rims can give you a indication of bearing condition
Age of battery
Tyre ware
Camper rubber seals
Leaks in water system
Leaks in canvas.........Check seams and open and close "ALL" zippers
Wiring
As mentioned above, if owner can not provide receipts, except that you will have to replace it yourself for peace of mind. When I purchased my camper I took the owners word (a lovely elderly man) that the bearings had been replaced prior to sale. I had them checked and they were close to being disintegrated.
I'm sure others can give you more tips