I currently use Google Voice for SMS, and it's not out of the ordinary to get messages in the middle of the night. Unfortunately, I can't currently use any ROM's that don't have the Motorola Battery Manager installed. That said, I can only use Fission (w/ MBM addon installed) and ZombieStomped.
Therefore, my question is, does CM7 always have data enabled? The other D2 ROM's out there, such as Liberty and Apex, only have data enabled throughout the day, while it's disabled between 9p and 6a.