1974 missing lock assy, workaround option??

[j_c_c]

I'm helping a buddy consider buying his first airstream and it looks pretty good but the door lock assembly is totally missing. Looking around online this is NOT a cheap replacement...

So tossing any need for it to be stock or close to stock without getting too ghetto, anyone have any easy ideas that don't require hundreds of $$ nor cutting the door to install a conversion kit?

If that's not possible, how would you fix it? The Inland kit? My buddy probably won't be up for that himself, so if anyone in LA area has done it, wanna give an estimate of what you'd charge?

Thanks team airstream!