Welcome to Roadsters! I have a couple of favorite storage spots, but FIRST, before we go there, you need to eliminate the 'under seat storage' immediately. Easy to inadvertently lose things there, a huge pain to get things back out. I used something like this Amazon.com: Drop Stop - The Original Patented Car Seat Gap Filler - Set of 2 (AS SEEN ON SHARK TANK): Automotive.
I used some pipe insulation, couple dollars at home improvement store.
i store a couple pairs of sunglasses and a couple baseball hats between seats.