On my '98 Coachmen Santara class C, the front clearance lights are powered from wires that come through the ceiling on the lefthand side. You have to at least partly remove the bit of curved carpeted paneling that runs up the front to the ceiling to get access to the connections. The wire I assume must run from there down to the rest of the RV wiring through the wall or something at some point, but I have no idea where that happens.
If you can find the color/stripe pattern of the wire for some of the other clearance lights, you might be able to track it down in various wiring bundles and see if there are any obvious broken connections there (or with associated ground wires).
