what better combination than a folding bike and a folding trailer? i've been using the actionbent folding trailer for a few months with my schwinn continental and it pulled ok...i found that i could never really stand and pedal without getting the wobbles....for whatever reason, standing on the BF with the trailer is a much more stable experience...i thought i would have a problem with clearance because of the smaller 20 inch wheels, but so far it doesn't seem to be a problem...my .02
I have an Actionbent trailer and a Bike Friday and was thinking about doing the same thing. However, Bike Friday's web-site does not recommend using Bike Fridays with single wheel trailers. Apparantly, it puts too much stress on the chainstays (according to Bike Friday). You might want to check it out with them before continuing to use this combination.