Moonrats! Evil moon-powered intelligent vermin/animals as PCs?

[seedjar]

I was thumbing through the MM2 and found these guys on page 151. The picture is so cutesy and hilarious that I was thinking it might be fun to make them into a playable race and run a campaign as such. In particular, they seem perfectly suited to a dark-humored evil game. Thoughts?
For typical settings, it would limit the times the players could act, as during the day they'd be of ordinary animal intelligence. But in the case of a setting like Eberron, with a staggering 12 moons, I think it could fairly be said that there's enough "moonlight" in the sky even during daytime to confer at least a bit of the rats' bonuses. Even without that fiat, I think it could make for an interesting game, especially if the characters were explicitly aware of their dependence on moonlight and planned accordingly.
The first thing that occurs to me is that a -8 Charisma penalty would be really harsh for a playable race. Also, how should base scores be determined for Strength and Int, such as in the case of determining skill points?
~Joe