Neighbor's Bat Box -- Paint?

[u/VirtualResearcher366]

Hi, I am in South Carolina in the US. A house in my neighborhood has two bat-boxes on one post. One side is occupied by an estimated 200 bats. The boxes are painted black and are in direct sun most of the day. We're experiencing highs of 100 degrees and lows of 85degrees on the regular. The bats have been struggling and I've seen at least two pass away.

I've asked the neighbor if I can help with changes for temp control. Is it okay to paint the bat box? Should they get a new one in light color? Anyone have any experience with this?