You're solving all the problems and it's turning into a neat, well thought out bike.
It looks obvious that you won't be using an airbox. It seems to me that there is now an opportunity to mount the battery below your new "X" brace ( A sealed gel type, laid down.)
With your ECU very nicely mounted under the seat, that leaves the under tank cavity competely empty.
I'm not sure what sort of tank you will be using, but if it's a Monster one, then it would be possible to do something I have always wanted to do.....Blank off the cavity with a welded in plate to dramatically increase the capacity.
The cavity would need large holes drilled above the plate so that it filled and flowed, but it would remain in place to act as a baffle and still carry the pump and filter.
Of course I have no idea how you will be using this bike, so I don't know if extra range would be any advantage to you...Personally I wouldn't be able to resist it...
