I'm assuming you have an F53 chassis like mine. That said the master cylinder and brake fluid reservoir can be reached through the front drivers-side wheel well.
Ditto with wolfe10 clean and lube your brake caliper slides. I had the same problem once because of sticking brake calipers.
Apparently the people that engineer these things never ever have to work on them themselves. Aren't Ford's fun!
Steve
PS If I were you I'd find another place to work on your RV. A place that actually had competent people working there.