The only access to the plumbing is through the tiled shower wall. The back side of the plumbing is not accessible.
I've seen conversions where they break out the area around the old valves and then install a large remodel plate over the resulting hole. This doesn't look great and you also wind up with the shower valve much lower on the wall than would normally be installed.
Has anyone ever done a conversion where they mounted the single valve higher on the wall without access from behind? Can you make the hole for the single valve big enough to sweat the new connections but still keep it small enough to be covered by the standard trim? Wondering if using PEX might simplify things. Interested in a Moentrol valve if that makes a difference.
A hole will still need to be made at the old valves but I'm hoping it can be kept about 1 tile high. Old mud bed needs to be repaired and new tiles installed.