Any time you want to get rid of any critter or pest, read the tutorials on BugSpray.com. They're a large retail store in Stone Mountain, GA and the largest retailer of termicides in the U.S. They've got the good pesticides that pest control operators don't begin to use.

https://bugspray.com/article/aphids.html

They are easy to get rid of, and BugSpray.com sells the best products to rid yourself of aphids and any fungus that brought them to your RV.