The small car top Cat has been done before.

I had a chance to sit in a van going to some party with Hobie Sr. back in 99 at Carlton's regatta.
He was asking the people there " how can we get more kids sailing on cats".
He talked about the 10 and 12 foot designs he had worked on without much success.
He was very passionate about getting more kids sailing.
I remember him talking about how it cost almost as much to build a 12ft Cat as it did a 16ft version and that it was very difficult to get parents to buy boats they could not sail.
I don't think the boat is what will make the difference.
It seems that the kids that sail at clubs do so while the parents are having lunch on a big boat they never take out.
The Opti is like the VCR or video game at home. An easy babysitter.
We all need to keep trying to get the kids out on the water.