If you intend to use the product, Liquid Rubber (LR) on it, you must know if it is TPO, which LR will not stick to well (see their instructions). That product is for EPDM. Even with that you still need to use their special prep stuff, which greatly helps the LR stick to the EPDM.
I used LR on my 1991 which had some kind of deteriorated white on both sides "rubber" on it, that I took to be TPO. However some info says TPO came out in the early 90s, so I don't know if a 1991 RV would have it. Anyway the LR ( just that with no EPDM prep stuff) stuck so I got away with it.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.