This came up for us a couple of times as well, and the problem was more to do with the overall network design. There were some concerns around passing VLANs across the links.
Essentially we were told a MX would have to go at the other end of the link to handle the VLANs as they cannot be trunked across the link.
Luckily for us, it was easy to run a 2km fibre through conduit and use a basic MS switch at the other end.