I like the idea and especially the non-invasive approach of no welding or drilling of holes. Can also be modified or relocated at any time. Uni-strut is like the lego of the electrical construction industry, you can build so many things from it. There's also Superstrut if Uni-strut doesn't have quite the fitting you want. I'm thinking nylock nuts and maybe some Loctite would help? And as mentioned, probably inspect periodically.
This might work for building something for under the frame spare tire storage and probably a number of other things.
