Not a problem. Europeans pull camping trailers with 200d's.
Does it have brakes? I believe MB states that trailers above 1500lbs should be braked. I think 2500lbs is the load limit on a trailer for a 123. Don't know about the 126. Just make sure you have a decent hitch. I pull a small trailer with a bumper hitch on my 300TD but it's never over about 800lbs.