The only way to hold something this heavy in a way the would continue to retain it in a dynamic event like a hard roll over would be to build a frame work that the reciever mount could slide into and be pinned in place.
The frame work would need to go through more then just the sheet metal of the floor it would need to bolt through the integrated channel in the unibody structure.
Reciever mounts are really worthless IMHO for backcountry off road trucks. They take up valuble space inside the truck you really want for gear and require you to unload the truck in what is normally a bad spot in the trail just to get to the tool you need to recover your truck.
I would sell the reciever mount and use the money twards buying a nice front winch bumper for the truck that will give the Liberty protection and a place to carry the winch. The liberty is a bit light up front anyways so moving that weight to the front end will make the truck climb better and put the weight where you want it for better handeling while driving.
I got a bottle of Aloe after getting sun burned. It says "apply Liberally"... I'm not sure if this means other people pay for it and I use it, or I am to force other people to use it even if they dont want to because it's what I think is right for them?