Love Bug used the Bargman L-400
Lockset. They are very, very scarce. You may
be a able to get a kit on eBay for just the lock portion, but be prepared to spend some coin. There ARE new alternatives, but requires a bit of fiberglass work. If fact, we're talking about this exact same thing here: 1977 Boler Door Handle Replacement
BTW: Scamp never manufactured with a paddle handle lockset.
I wouldn't consider a broken lock to be a deal breaker, if everything else about the trailer is what you're looking for.
Best of luck