So as the saying goes: Look before you leap (ask questions). I solved this problem myself by removing the wheel and sticking my into the space between the brake drum and front inner fender. I was able to see one of the studs mounting the lamp housing and (with great difficulty), reach around to feel the other. Fortunately, neither nut was seized and they came off with a socket wrench. Thanks for reading, and sorry I hadn't looked more carefully before asking...
