I too like the idea of being able to lock up my truck to protect all of my other things I bring along on my trips...
Of course you might be able to install something like this to have some safe storage areas and not use your tail gate...

Google image
I still like to have my truck tail gate lockable and closed up when not hooked up to the 5th wheel...
In my case I also use my OFF-ROAD POPUP trailer a lot more than the 5th wheel. I have a rear camera in the Ford Emblem mounted on the tail gate. I certainly could not operate without the use of my rear camera - Makes hooking up to the OFF-ROAD POPUP trailer a breeze...
Roy Ken
