I did a quick sketch of how you could modify your panniers to be rollers:

The Aluminum may bend a bit under load, but at a certain point the stuff in the bag will keep it from doing so further. The only problem with it is you guys don't have the hardware or free access to the necessary tools.



Another [silly] idea, you could take one of the 4 wheeled walkers like pictured below, then add some small rod/ tube stock to it so your panniers could be hung from the sides like it was a rack. I am sure it would look hilarious with the gear from both of your bikes hanging off it!