First, unless there is an overriding enviormental concern DO NOT COVER the RV, covering it traps moisture which encourages mold and mildew.
Second. I mop my roof spring and fall with Spic and Span if I can find it, or any good floor cleaner if I can not, I use a Soft Bristle (Van Wash) brush instead of a mop but otherwise thing Kitchen floor. Normally I Was taught to mop with cleaner then again with clear water.. I use a garden hose and sprayer for that pass.
But unless there is an overwhelming enviormental concern Like Salt water spray DO NOT COVER.