I think some confused by the question.
I do have the RV powered all through the "load" from the charge controller. This is a quality 20amp one, not the $14 things out there. The reason is that the controller will shut off when battery voltage gets low so the batts done get too drained. I assume I can pull 20 amps through the "load" terminals since it is a 20 amp unit. My camper should never need 20 amps.
When buying quality controllers, they get expensive, so I do not want to buy more than I need. 10 amps are cheaper than a 20 amp, but if a 10 will do then I have no reason to get anything bigger. Remember the lift motors will be on a different controller and battery than the RV.
Yes, many are correct that a battery will be sufficient to power the motors, as I have been doing, and already well know.
Fuses would tell me how many amps it is not pulling, but do not tell me the amp draw.
The fuse could be double the draw.