Bruce -
I would call Bill Fox (the owner) in UT at (801) 897-0625.
He's a really nice guy and will most likely answer within a few rings (he did for me on 2 separate calls) even though he's at work - the battery locks are a side enterprise.
Anyway, he may actually be able to easily build one to your specifications. Of course that's just a guess, but I would call him & ask if I were you.