Adding multiple variants before filling out custom form?

Hi. I have a sailing program. We want to offer a set of dates in the fall that people can sign up for sailing. We want to give custoemrs the option to pick 1-6 dates. Each date can have 6 students. For the set of dates as a whole, I need to know the student's name (who is not the parent who is paying).

So I'm trying to setup a product (or products) that allows for this kind of purchase. I need a way to have them add the qty of dates since it's priced by the # of dates selected, and then tell me which dates they want to pick. 

I have an almost working version that uses a single product, allows for multiple dates to be picked as the quantity, and then a custom form to specify the dates chosen. but this approach has a few gaps because the qty is not linked to the dates selected.

• If someone doesn't match the quantity to the number of dates selected in the form, I'll have to go back and fix it. 
• I can't know without monitoring directly if we sell out for a given date. 

Maybe what I'm looking for is a custom form at the checkout stage, not at the product selection stage. Not sure if that's possible. 

Any ideas welcome.