Nice! What I'm thinking is something along the lines of .242 drag in the pictures. Probably no greater than 4' extension as to keep it maneuverable/easy to park.
I did read up on Bamzippow's post... very interesting stuff. I don't think a single wheel is what I want to do for a variety of reasons. Notably, I want to keep this thing light enough to remove easily for parking/unloading.
Maybe a hinged arrangement is best. But then no storage for the pimp bike....
I actually have a set of those load jacks on the old popup I could steal for this. Maybe even put a heavy duty caster wheel on each to aid in hitching/unhitching.