Clear enough, turning on the gas through the flipper is out of question, taking your advice as you mentioned in a post above and placing the valve at the back. All the rest of the stuff will also be at the back.

I get your point re. dump valve, but I'm not sure if I'm making myself understood...what I'm trying to explain is that the PRV will be open all the time, not through myself pulling on it though, but through a mechanism which will hold it open for as long as is required, ie I'll close it just before I pressure up the system... I'll post a sketch to explain myself better.
Obviously, if you straight away tell me its not allowed, then no problem, I'll find a place to squeeze in a separate dump...