If they are the 12 volt interior lights that most RVs of that era came with, they don't unscrew. They are automotive type...they are pushed, turned 90 degrees, then pulled and they should come out.
When I bought this '02 Winnebago I had several of the lamp bulbs that were burnt out and it took some finesse to remove them without damaging anything. I didn't think about it at the time, but dry lube would have worked I'm sure. I did have a fixture that the wires came loose so had to pull that off the wall to find the problem.
I have those small 'flood lamp' style bulbs in the bedroom that are 12 volt (so they are quite a bit smaller than a 120 Vac traditional flood lamp) and they too were very difficult to get out. Very little room for my fingers. Eventually though, got them all changed. Over 6 years now, have had to replace a couple over the bed 'cause I use them to read by for a couple hours every night. Most of the other bulbs in the house are doing fine.
Amazon and eBay carry the bulbs. Or LED replacements.
The wall mounted fixture bulbs are 1076 double contact (but only one filament). The flood lamp style are 1383, single contact, single filament. At least in my RV.