Cushwa Basin parking's likely to be crowded. There's a smaller lot a bit downstream by the lockhouse, but I've never checked it out so I don't know how crowded it gets. That is a nice ride, though, so I could be willing to brave the crowds at the beginning/end. The other option would be to drive a bit further and meet at Fort Frederick.

Janice, how long does it take you to drive to my house (just to estimate your total driving time)?