Multiple Subscriptions per user

Hi Gang, me again! Hoping to get some advice / direction.

I am currently using Membership to give a monthly subscription to a series of podcasts, but right now, a user can only pick one podcast at a time. I have an access level set up for each podcast, and one all-access pass.

I am looking for a way to allow a user to add a second podcast (or a third or fourth) to their account. I see that a user can only have a single subscription, and adding a subscription for every combination of possible levels would get untenable very fast. (With 5 podcasts, there are 32 combinations. with 10, there are 1024, with 20, there are over 1 million)

I started looking at switching over to MarketPress eCommerce to treat each podcast as a product with a shopping cart process to give access, but that plugin doesn't support recurring billing.

Is there a way to either allow multiple access levels in Membership, or add recurring billing to MarketPress? Is there another option?

Thanks all!

Joe