Got the Shorai battery and luckily it fits under the tail section as I had hoped. It only weights about 3 lbs so it shouldn’t be a weight issue. It will just be a matter of running the wires in discreet places.
I bought some aluminum to make a cage and bracket for it.
I cut the two ‘L’ brackets to create bumpers from preventing the battery from moving forward or backward.Then started bending the aluminum strip to make a srtap like bracket to hold the battery from moving left/right or uo/down.
I marked the footing and drilled some holes. I purposely offset the bracket to not interfere with the outlet on the battery for the Shorai battery tender.