Your work looks 100% fantastic, I would love to see this stuff in person.
you say it might be hard to tighten/loosen the tuner , so like Michael caine "ive got an idea"
This might sound like a daft idea,
but here goes.
instead of having 4 bolts hold the complete tuner in place and being very difficult to get at to tighten/loosen.
what if the top of the tuner had a round threaded piece to attach it to your 4 bolt plate ?
you could still have your 4 bolt adapter type thing, but then the box type tuner with a female thread and
a male thread on the 4 bolt plate to the adapter or even a push up and twist into locked postion..
By having something like this you could even have different lengths of threaded collar to give more or less tuner length for different applications ?
Its just a thought and probably another one of my stupid idea's that just make swarf.
I am no engineer by a long way, and like most people could never in a million years do anything like this.
but from the work I am seeing you do, this would be a easy thing for someone like you to make .
if this sounds daft, don't panic. I have loads of ideas that don't work
and please don't take this the wrong way.
phill