Our set up is similar to what Squiffy describes above and operate it in the same way. I’ve never thought there was anything wrong with this, as it seems that is the way the system was designed. MarkJ do you have a gas manifold fitted inside your van that maybe could be used to isolate the gas...
I’m not the tallest of people and I find I can reach all of the screen by standing on the front wheels using the mirror to help get up and to hang onto. Then it’s Elbow grease a e cloth hot water and finish with a Chamois.