Thanks again for the response, Phil ... I've seen a few videos showing this setup move a 5er around, but I still kind of cringe, envisioning the tug walking out from under the kingpin, with just the vertical pipe, and then think that if it doesn't, it must be applying a lot of push force with the braces to the landing gear. Maybe it's just an over-active imagination on my part.
I envision using a tripod or 4 legged stand that spreads out the load and stabilizes the power tug, but apparently I'm over-analyzing the situation.
I'll look at the Power Caster a little closer.
re: wintersun - which brand unit did you go with?
I do have a spare aircraft tug (12v battery powered) in the hangar that I keep toying with re-purposing, but it's not built to carry any kind of weight load - simply a "push-me pull-you" affair.