Not gonna lie, I got really worried when I saw all the 3d printed parts. Glad you mentioned it’s just for test fit. I love that you took the time to mock it up for test fit.
For battery amps for your packs , check out this thread for some calculations.
Basically your amp draw limit will be set by your cell types discharge limits times the number of parallel groups you have.
For space between motor and board, I usually just stand on the deck at full lean and give myself an extra few mms of clearance.
Welcome to the forum dude!