[Jabe]

Lets see, things that makes battery swap slower are, opening and closing straps (velcro), disconnecting and connecting plugs, taking off body and putting it back. So you need "6 points" to swap batterys.
So you should get rid of velcro straps and use some locking mechanism, here you save "1 point", you should mount battery connectors, so when you slide battery in or out, you dont have to disconnect or connect, those disconnect and connect "by itself", so now you have saved "3 points".
Combine here machanism that allows you to swap batterys whitout touching body and you have saved "5 points".

Im thinking, battery tray, that slides from back of car (need hole in body), quick release (like in your picture) and mounted connectors, you would need somekind of quide posts where battery tray slides, so it matches those connectors.
Just open quick release and slide battery out, then just slide new battery in and go go. You should be somewhere in 5secs, in battery swap.