Its a good idea. Seen a couple of good ones, best so far was a 109 with a 109 based trailer. Looked ace. I'm planning one at some point but will probably use a sanky as the base.
BUT - if I were using a 110 I'd cut it at the back of the front doors, or just in front of the bulkhead.
Make an a frame off the chassis from there, build a stop end to the trailer (poss using part of the bulkhead), take the sloped section off the roof and move it back to line up with the new length.
Not done any of that, so it's probably no help!