I drive a Forester.
I have gotten enough gear for 3 divers in the back and the 3 divers in the front.
I use my back seats as a dry area when I go diving.
Anything that I don't want to get wet stays in the back seat.
That leaves the cargo area for all the gear that is getting wet.
I like that you can get a rubber cargo {wagon part} area tray.
{You can also get rubber floor mats if you do a lot of hiking or just like getting your feet muddy}.
I load all my wet gear in the back on the rubber tray.
When I get home and get the wet salty gear out.
I pull out the tray and give it a rinse with the garden hose.
Then I toss it back in the cargo area.
This has worked well for me. The only issue is ~ when you stop after a dive for lunch or coffee with your buddy ~ the car gets steamy inside.
Its not bad if you remember to leave a few windows cracked.
I am not a tall gal so I can use the hatch as an overhead cover when I gear up in the rain.