Sending a quarterly batched email program

I have an email program that needs to be sent from 7 sources (sales reps), 4 times per week, for 11 weeks.

Ideally, we would select leads from 7 smart lists that contain the leads sorted by rep, and then the daily recipients would be pulled from these lists as random samples.

The problem is that there doesn't appear to be a way to batch emails this way in Marketo. The random sample filter/choice would be a great option, but it only allows for selection by percentage of eligible records, not the first X records. This means that in order to select the appropriate amount over the course of the program, you'd have to select: 1/11, 1/10, ... 1/2, 1/1. This is clearly another non-ideal solution, and would only break the group up into weeks, not days.

Any ideas on how I could accomplish this without creating 7*11*4 (308) individual lists and as many email sends? It seems like a pretty sloppy workaround.