I just recently sent my (N Code) cat box to this place (RM WORKS) as a prototype for a under belly tank. Postage paid by John McKee. They have had it for a few weeks now. So I think old John is way ahead of us on the belly tank issue anyway.
We have a cat box here that someone from Gig Harbor shipped to us. I have a couple of R3's in the area and am waiting for it to be nice enough for them the take them out.
No need for the guy in Kingston to ride over just for that. If he is coming by this way on his way to elsewhere then yes I would find time to take a look at it and to see what the existing fuel system amounts to.
It would seem to me that you could drop it down to where the stock cat box used to reside, a small sealed battery box, a you would have lowerd yoru CG a lot more and freeed up some space under the seat for other stuff ( like an extended range tank when youve removed your airbox as well)