I wouldn't dump a whole of money into an expensive lock up system. A good well placed #2 screwdriver will open most TT doors first try by bending back the ALUMINUM frame at the door jam. Then it pops right back in place haha...
On my POPUP the easiest way to get in is to slide your hand behind the VELCRO around the door and open from the inside hehe...
When I am carrying groceries it is easier to do this instead of trying to fumble around in the pockets to find the keys.
I think the locks are there only for the honest people and makes you feel good... In all my years of camping since the early 50's I have never had any problems with fellow campers
I even enjoy having the same lock key as the neighbor - Sure keeps him from being locked out sometimes haha...
My truck has the push button door lock setup so we keep all of our spare keys and valuables inside the truck. It is easy for us to get at when needed.
Roy Ken