Whoa - just notice the "no access to the pots" - a bit of a schoolboy error. The answer to one of the Qs "In order to create the sealed cavity to the correct volume i had to include the electrics cavity, if i had added an standard access this would have compromised the cavity." is a bit odd - even if that was the case it is no excuse for making access to the pots impossible.
Reading the rest of the blurb, it seems the bridge p/up isn't a piezo in the bridge as I guessed earlier from the style of the bridge, but another MM type buried and not adjustable.
Just plain weird.