would help if we knew what 5th wheel year / make / model
roof mount is done by adding a solar "gland" BOX or other method
good place to add the connection is down the back of the fridge or inside a existing wardrobe.... you will need to cut/drill your roof
but it also needs to be near battery
Newer 5th wheels may have wiring in place "Solar Pre-wired"
PLUS if you install a system it depends on how much power you want to use each night ... don't even think you can run a air conditioner off battery and solar without spending a ton of cash
Moved thread from the General Community Discussion section to the TT/ 5th Wheel section's Rockwood sub-forum since the OP's questions are specific to a Rockwood product and are not general community questions.
once the wire gets to the compartment drill a hole / feed the wire inside
use lots of sealant to fill the wire/hole
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If there is front bedroom I would run wiring through roof and then trough the front wardrobe (if there is one.)
use a gland or other fitting for the wires on the roof