This is a sad case of the OP suffering because of another Dog owner who wants to control everything.
Dogs on leashes as most of us know are generally pretty territorial. If you took the same dogs and let them run around unleashed either in a big field or a fenced area they would be fast friends and playing.
As dog owners we should be helping each other fight the increasing tendency of RV Parks to be Dog unfriendly. We should not be needlessly escalating minor issues to the parks. If this behaviour continues then pretty soon parks just wont allow dogs.
So even though little Fluffy got growled at by that big bad Labrador just relax. Work it out amongst ourselves and dont escalate this kind of thing to the park. Deal with the other dog owner. It's in all our best interests.