We've lived in leaky 5ers. I would find a leak while moving furniture and vacuuming. Then DH would go redo caulking on the roof and around end caps and wait until the next rain storm to see if the area stayed dry. We took one back to dealer on our way through town and they just added more caulk where he had. So decided we'll never do that again.
But if you don't catch the leaks early, then you could be looking at major repairs under the skin.
That is also something we've done, remodeled our homes while living in them. It's not difficult, put things in totes to keep them dry and out of sawdust. Then remove the ceiling panels to see if there is any hidden damage. The wall or ceiling panels can be replaced via RV Surplus or ordering through a local RV Dealer or Mobile Home Mfg.
2014 DRV Mobile Suite Estates 38RSB3....our custom home
2014 Ford F450 KR CC 4x4......his office
2015 Lance 1172 TC.....mobile Motel FOR SALE
Working Fulltimers since 3/2005
"Shoot for the Moon! Even if you miss it, you will land among the Stars."