[thenewkid64]

Two options:

1:take the trailer to the locksmith!

2: Take the trailer to a rally and see if anyone there has a key that fits yours( I bet someone will) and get a copy made pronto.

If you have an airstream dealer near you you may be able to "find" a key that fits for a bit of gas and time. Most dealers seem to have a box of "Spare" keys that you can go thru. If there is a number stamped on the lock itself you just have to find the corresponding key. There are not that many diffrent ones out there.

Good Luck