I was thinking of this as well (as I've got a few SSCs that are behaving... erraticaly... in the yard right now). There are a couple of questions though. Do you have to have the RGBs connected to program the SSC? If so, how many? Do you need as many as you are programming the dongle for or can you have less? If you can do less, then it seems to me you could mount a couple of RGBs on/in a box, the connector, a few D Cells and be good to go. The RGBs are drawing about 29 mA each (according to the wiki), and D cells are usually around 8000 mAhr, so you would have plenty to go around. Or, a couple of 9Vs (through a 12V regulator) for less space. It would make a nice little tool, along with a laptop or netbook, to be able to rapidly program in the yard, or in the comfort of your workshop without the need for an extra active/passive hub.
Of course, the cost and trouble of all this might just be more than having a spare passive hub in a box.