I have a cell phone that says "Unplug adapter to save energy". If you have a wall mounted USB port, then you will have no way to unplug it without shutting off the circuit breaker, or in the case of a switched receptacle, then shut off the switch to keep the USB plug from drawing power all night - when not in use.
A better way is to just have several USB adapters. Then plug that in when you want to charge or run something with a USB port. Unplug when not needed.
With a RV, have you ever removed one of the receptacles? Most are not like a house, with a separate box and receptacle with wire connections inside the box, with a separate cover. Rv's typically use a RV style that is all in one, that does not have a separate box or cover. So I can not see a "Typical" home receptacle ever fitting in the RV opening (that normally will not have a box to contain the electrical power).
I have installed a new box and new receptacle in a RV, with a cover. It takes about 4-5 minutes to install one, compared to about 45 seconds for a RV style receptacle.
Good luck!
Fred.