Under fender storage

It sure seems like there is a lot of room and clearance between the rear tire and the under side of the fender. No I haven't tried to measure at full compression. Yes, I know it's dirty location. It seems like it would be easy enough to mount a hard, waterproof container for seldom used items ~ spare tubes, first aid, air pump, tools.

Has anyone measured the clearance at full compression? I'm thinking about a couple of tool tubes.

I've been tempted to find a way to mount an MSR bottle or two up there but haven't had the time nor serious desire to do so as of yet.

I got the standard agri tool tube and mounted it on the left side frame, replacing the stock tool box. At least I have room for some tools now. As for the under-fender idea, after holding the tube up there, I think the size and shape is incompatible. I haven't given up on the idea, but the chances of finding an ideally shaped and sized, water-proof container that can be securely mounted are mighty slim. Funny how big spaces look until you start to fill them