I believe you can't apply Comms Limit dynamically to individual records.
Before Comms Limit was available, I had set something up to prevent my nurture campaigns to be sent if the lead had already received another email. It wasn't pretty but it did the job! It had:
1. A "Daily Email Count" custom field
2. A trigger campaign that added 1 to Daily Email Count every time an email was sent (Email is sent, Email is any)
3. A campaign scheduled to run daily that reset Daily Email Count to zero
4. Nurture campaigns (this was before Engagement Programs) that checked that Daily Email Count was zero prior to sending an email
This may be over simplifying things, but maybe you could set Marketing Suspended = TRUE when an email is sent to the prospects that fit your criteria, wait one week, then set it back to FALSE?