@songofjoy I can't see your entire layout or how tall the space is under there, but here's an idea for the heck of it...
There are these truck bed pull-out drawer type systems, where you have a flat platform that pulls out, or drawers that pull out or a combination of both. So, you can be at the back of your truck bed (usually with a canopy over it), and you grab a bin and slide it toward you. Then, you can reach everything in the bin. The bin stays attached to the truck bed. Maybe you could retrofit something based on this idea.
Like I said, I don't know if that would work over your roots, or if you would have enough space for the pulled-out bins, or if it would cost too much, etc., but it might be a nifty way to use that space under there for storage and be able to access it without having to crawl around (if you can't stand up down there).
Here is an example of what I'm talking about:
http://www.cabelas.com/product...
