I guess I should back-up a bit.
The original problem is a faulted fixture on a 3-pole CB, which is causing the whole area to lose light.
I'd like to do this as simply and inexpensively as possible.
I'm wondering about retro-fitting fuse holders at each ballast.

BTW, the set-up consists of a 10 rectangular remote ballast enclosures, each of which houses ballasts for 2 fixtures. I've heard that there used to be dual-lamp M-V ballasts, but I don't know if these housings contain those, or 2 separate remote ballasts.
The problem is that I can't access the existing equipment without a lift and I don't want to rent a lift until I'm ready to solve the problem.
Energy savings aside, the only reason I thought about fixture replacement is that I don't know if I can retro-fit fuse holders. I'm having a hard time finding aftermarket fuse holders. But, if I can install them, that's what I'll do.