Remember back in '87, RV's didn't have nearly as many electronic devices (i2VDC and 120VAC) that they do today.
Maybe the few 12V items had inline fuzzes. That is the fuzzes were in the positive wire and were physically located close to the device that it was powering. As for the converter maybe there is a single 120V breaker located on the converter itself.
Maybe this will help, let us know what you find out I am curious.
2005 Dodge, 2500, auto, 2wd. Pac brake PRXB. CB, Max Brake Brake Controller, Rhino Lining, Aero 60 gal. replacement tank.
1998 Hitchhiker ll, mod#31RLBGBW, RBW L'tl Rocker Hitch, Generac NP50 G generator