Salman, there's several to choose from in the open area.

There is a nice launch at the Marblemount Bridge, another at the park in
Rockport, and for short drift you could launch at Fabers (North side). There's
a couple more, but those are the best.

For a take-out, I'd use Concrete (by the Baker River).

March and April will be the best months.

As for the Sauk, it can get thready, so be sure of your route before you go.