Vintage Pfieffer trailers?

To anyone whom can help,

I just acquired a DG101g a few weeks ago, and when the a-hole left, he did not give me the keys. When asked he said he put them in the front of the trailer, but nothing there, and claims they are not in his pockets.
So after looking at the glider, I closed the back door thinking it was unlocked. It is locked, do not understand that, but can't get it open. So now have a glider that I can't do any winter work on because I can't get into the trailer and the fuselage is a tight fit out the front.
I have a vintage Pfieffer trailer. Hoping you might have a matching trailer? Keys? Let me know! Thanks!

I know keys come in many different shape and sizes, but these are original locks as I know, and hope there are a limited amount of choices for the vintage Pfieffer. Suggestions welcome?

-Brian