The interior wall on mine is covered with what feels like a wallpaper. I know from owning homes and kitchen remodels, it only takes some steam to remove it. Since years of condensation caused this to happen in yours, why not remove it all and repaper? Have you clled Aliner company to ask them? The A Frame FB group has many Aliner folks in it who my hve experienced what you have goimg on now...would be interested to know what you learn & how you resolve it! My trailer is a 2012, so hoping its a long long time before I see any issues like that.
2012 FR Flagstaff T12SDTH
1996 Shadowcruiser Pop Up Truck Camper
1967 Newell Motorcoach
2003 Ford F150 5.4 V8 Triton Super Cab
2004 Nissan Titan LE 5.6 V8 4x4 Crew Cab