I scanned thru and didnt read most post bc traditionally they are answered by ppl without first-hand exp...
I owned a fiberglass TC.
Sagging is common for fiberglass shells and expected. This one looks good, and I would expect more sagging at the AC unit. Sagging can be fixed,or just leave it alone.
Remember, the fiberglass shell is basically a boat. boats can sit in water for decades and not leak. A sag will never leak, only a crack.
The window rubber trim is common and always happens.
The price seems about ballpark right for a Bigfoot, but compare it with others for sale.
The only place that camper can leak is at the penetration points, holes, screw holes, vents, windows. Not even the seam of top and bottom can leak. Leaks at holes or vents is not a camper issue, it is a maintenance issue and easily fixed.
These fiberglass campers can leak and have little damage as the structure is, afterall, fiberglass. Just some cleaning agents and a rag can fix most water leak damage.
You will want to look for anywhere there is wood to see if the wood is water damaged.
Eterna bond tape is great stuff, but it does leak where the tape over-laps itself. I would rip all that tape off and re-do with Lap sealant, or you could just put Lap sealant on the over lapping parts and likely have a good seal.
