Has anyone had any luck on installing a battery on a 90's klx250?

Looking at installing some accessories (Flood lights, USB port, ETC) and was wondering if anyone has installed brackets from newer models (maybe?) to adapt a battery to the frame.

Ive seen some DIY battery boxes but don't like the look of an exposed battery/battery box. Also noticed the ignition switch is a 4 wire ignition which tells me that installing a battery then splicing a wire from the output of the reg/rec wont have any problems there.

Does anyone have any experience with this??