Removable Pelican case mount for top of Tonneau Cover

I have a diamondback cover and want to be able to mount a large pelican case to the top securely without using straps. My goal is to be able to mount the large pelican when I need extra storage and remove when not using it. It needs to be able to lock as well so no one can remove it and allow the covers to still open

Thanks

 

Do you have some sort of cargo tie downs mounted on it? If not, I'd look into something like an L-Track system (ex. https://www.uscargocontrol.com/shop/Enclosed-Trailer-Accessories/Airline-Straps-Hardware or http://www.macscustomtiedowns.com/category/VersaTie-Track) then use a mounting stud such as this http://www.macscustomtiedowns.com/product/m10-threaded-stud/VersaTie-Fittings

They make a knob for it as well that wouldn't damage whatever you have in the case, if you have the room for it. http://www.macscustomtiedowns.com/product/four-prong-knob/VersaTie-Fittings or just go inexpensive and use an acorn nut. Note, those companies in the links are just examples I found, I have no experience with them.

You'll have to drill holes in the cases but just use rubber backed fender washers on the inside and you should be good to go.