Did a test fit up of the drivers seat with the mounting bracket and my helmet on.
Bad news is the mounting bracket isn't quite right - just a tad off center with the steering wheel to the window side. Meridian are going to make a few tweaks to get it sitting where I want it, and by raising the front a little will give my girlfriend a bit of extra height when the seat is slid forward.
Good news is I fit! The double diagonal cross in the roof is well out of the way my head sits up in the void perfectly. With the seat a little off center I am very close to the other bar but once the new bracket is in it will be spot on.