Just a few things to consider even though my experience is apparently a rarity with this sort of setup. I bought a Samsonite F'Lite case last year, which is right at the 62" limit, and built a trailer frame based on BikeFriday's design. However instead of setting my trailer wheels way in the back I moved them forward a little to reduce "tongue weight" yet still allow me to detach the trailer and wheel it around in an almost upright position.
One point of failure, having occurred on the very first day, was that the air chuck that screwed into the BF's frame broke leaving the threaded portion of the chuck in the frame and no reliable way to attach the trailer to the bike. Also, even with the reduced tongue weight of my trailer, the connector hose (fuel injector hose) was still wearing quickly and probably also would have failed within the first couple of days. The air hose idea is a novel one but apparently not up to what I can dish out. My approach was to use a more traditional hitch design with a heavy spring (in lieu of the hose).