But it doesn't matter since in this scenario each chassis is powered exclusively by the respective panel. How hot does a black panel sitting in the midday sun get? That's your equilibrium temperature. As long as it's within the operational limit of the device there's no problem.
The reason earthbound DCs are difficult to cool is because of density. When you match up panels to devices and shelter in their shadow you no longer have anywhere near the same power density.
The reason people don't do it here is because it's too expensive.
For the record the equilibrium temperature in earth orbit is above freezing but below room temperature. Cooling won't be a problem at all unless you bring along a self contained power source. Heat distribution however might be - you will need an efficient yet lightweight construction to spread the heat generated in the chassis across the entire solar panel.
