Depends, CruiseAmerica does not require you to clean up the RV exterior. Most RVShare and Outdoorsy rentals may also have similar policy. If the RV exterior is not too dirty then it should not be an issue.
However if you expect to drive through places where there are bugs and dirt then you should negotiate with your RV rental and perhaps agree on a price where you don’t need to clean the RV exterior.
Discussion on CruiseAmerica Exterior wash policy: