Many, many years ago I dropped my car off to have some work done. I couldn't get there before the shop closed, so I just had them leave it outside, throw my keys on the floor. Asked my wife for her keys...."Remember last week when we went to the amusement park? I tossed my keys into your glovebox so I wouldn't have to carry them all day", she said.
I carry a spare door key to truck in wallet. Spare trailer key in truck. So, as long as the wallet isn't in the trailer (I leave it in there A LOT when camping) I should be ok.
I also need key to lock trailer door.