At the 2024 Ouray invasion I got drawn in the raffle for one of these:
https://www.rhinousainc.com/products/ul ... -organizer
It's a foldable tool organizer. I carry a smaller tool box but it is in the back and wasn't always easy to get to.
Turns out this Rhino organizer fits nicely under the driver seat (manual, not electric). I can't 'fill it to the brim', I think it would get too 'fat', but I tossed in all of my wrenches, pliers, screwdrivers and a 3/8" drive set. I also included some tie wraps because they are tie wraps. Basically, it is most of the stuff I will need for a 'quick fix'. It has a few compartments, I left one empty with the idea that I use it to 'hold' any tools I have used for the job at hand to keep them easy to find.
I used a bungee cord at the front of the seat frame to keep it from sliding out while braking hard or going down hill off road. It also has a couple of eyelets so when I am using it I can use the same bungee to 'hang' it if I want.
And now I can move/add 'lesser used' tools to my tool box in the back, like snap pliers, hub sockets, large C clamps, etc. I left the 1/4" and 1/2" sockets in the regular tool box along with the hex sockets and other misc stuff.