You would need to come up with some mounting means, like make them from conduit or something, but I was just in Harbor Freight today (my local outlet, where I cannot escape without buying something...) , and they had some really nice sized/shaped, beefy boxes, with handles and such, for very little $$, like a pair for less than $100, and they look "Nice", (robust, but nicely made)...and would be actually perfect....
https://www.harborfreight.com/tool-storage/all-other-storage/4800-weatherproof-protective-case-x-large-64250.htmlhttps://www.harborfreight.com/tool-storage/all-other-storage/3800-weatherproof-protective-case-16-516-in-63927.htmlI wish they had one of the "big ones", but looking at the others, they are as good, if not BETTER, than the Pelican cases I've seen, that cost 2x$$$ more..
here's the one I was hoping they had,
https://www.harborfreight.com/tool-storage/all-other-storage/5800-weatherproof-protective-rolling-carry-on-case-x-large-64819.htmlI didn't go in there for cases, I went in for a battery operated fuel pump, to drain and refill bike tanks ($10), and ended up strolling around and looked at those boxes.. perfect timing for you...
I'd buy that big one, and turn it it a "universal" trunk, that I can swap out from my C10, and my old KZ1000... I'm sure it would work fantastic.