You could try a lithium based battery, pretty small. Just make sure you regulator is working well.
Or an agm mounted just about the swingarm pivot would work well too. I know some people have modified their fuel tank to hold a battery but that would cost a fair amount of capacity loss.
The ride IS the adventure. The destination is just to get gas!
I'm 6'3'' (33'' inseam) ,superbike bars and stock controls. But I'm on an F model with the flat seat. Your seat with that hump in it probably brings you closer to the controls and I could see that crowding you a bit.