Only allow specific products in cart - pre-sell

[gsgreenberg]

Hi, I'm trying to pre-sell some new products before they arrive in my warehouse.  Due to a number of logistically issues related to this, I'm trying to see if there is a way to isolate these products from my other products.

I want to force the customer to only order pre-sell items or ready-to-ship items in a single cart.  Not to mix pre-sell and ready to ship items.

Regardless of if this is a good idea/UX, any thoughts on how to do this?