Possible to assign queues based on a target volume allocation rate?

Summary:

Rule to assign incidents between 2 queues according to a set target allocation rate.

Content (required):

Hello all - we're looking for help setting up a rule to assign incidents to one of 2 Queues based on a target daily volume allocation rate. For example, we may want to send 40% of all incidents to and in-house queue, and 60% to an off-site one each day, without limiting the types of incidents handled by each queue.

I am thinking this will involve setting up a custom field "AllocationTargetRate", and an incident rule that assigns each new incident to either Queue1 or Queue2 as they arrive depending on whether the volume allocated for the day so far is below, or above, the target rate.