Mounting ideas for EG4 indoor wall mount batteries on a sloped garage floor?

[johnSEA]

I don't think I would want to hang 850 lbs. of batteries plus what ever the Grid Boss/Flex Boss weighs, under a window no less, without
supporting a good bit of that weight with at least the front feet.

Yeah, that is a good point. If the ground starts shaking all that load trying to pull wall inward when there are two large holes above it without 2x6s running continuous to 2nd floor above. Definitely leaning towards supporting majority of weight of batteries with floor, some sort of platform (poured or built) or ledge now.