Cleaning caravans on site

Does anybody think it would be agood idea if there was somewhere to wash your caravan on club site's, where there was a platform so you could clean the roof properly, i would pay for the privilege as we put our caravan in storage where there is no facilities to do so, perhaps it could be exta revenue for the club.

ive looked at mobile valeter's but they use jet washes which which can damage the mastic which seal's your caravan, and also invalidate your warrantry or gaurantee