Not that it's difficult to imagine, but storage capabilities in an exoskeleton vehicle are minimal. I bought a few different options to try out and these are the ones I kept.
Velcroed (two wide straps) around the lower 1.75" cross member behind the driver (my passenger side has the battery in the same position). This has been my tool bag and/or beer growler tote.
I like it because it's off the floor and it's secured from shifting around as I drive.
Mizatto Bike Cup Holder, $13 for two
Velcroed (two narrow straps) around the middle 1.75" bar at the left front of the driver's seat, and the same on the passenger side. It also has a third strap I ran around one of the diagonal braces. This has been good for water bottles, cell phones, wallets, etc. Interior is insulated, which may help on hot days.
Roll bar bag
Snapped (four narrow straps) around the middle 1.75" horizontal roll bar. FYI, the straps are adjustable in diameter and in lateral positioning, meaning you can adjust it to fit around your roll bar configuration or other obstacles, like my 3rd brake light. I envision this as my track day tool bag that won't take up any floor space on the way to the event. It really is a very universal bag, with interior zippered pouches plus exterior mesh pockets on one side and webbing for strapping/clipping more stuff on the other side.