Shotgun mount options

Looking for a way to add a concealed shotgun/rifle mount in my truck. I have seen overhead mounts online, but I was wondering if anyone has found one that could be mounted on the underside of the rear seat (crewmax), or maybe modified an overhead mount to fit under the rear folding seat?
I know there's the lockerdown and esp underseat storage options, just not crazy about having to cut into the truck and would like to look into alternatives before resorting to that.
Whatcha got?

 

I think the locker would be the way to go on this if you want under seat. I don't see how using the overhead mount would work under the seat. With the length of a shotgun, you would have to be able to lift both sides of the back seat at the same time to gain full access to it. That would be a huge pain in the ass to try to do every time.