With the exception of the a few questionable drops, this is a beginning whitewater run from Tuxedo on down, with the advantage of a train or bus shuttle.
The river below 7 Lakes Drive is the shallowest part between Tuxedo and Sloatburg and becomes too scrapy somewhere around 300 cfs.
Downstream from here, before you pass under 7 Lakes Drive just upstream of a bridge (Washington Ave?), there was a surf-hole. At higher levels this might get really good since the river is constricted here. It looks like there might have been an old rustic dam here. Soon you will pass under 7 Lakes Drive; you can take out here.
Stony Brook will pour in from your left after passing under 7 Lakes Drive and the water will go dead flat. This is due to the Dam. It's a low-head dam, however, there's something in there to stop the recirc but all the way left has recirc and probably other spots as well. I ran just left of the recirc, right of the log sticking up. The rocks seem like they have good pin potential and there's junk in this dam. This is the last CL3 I know about.
Below Sloatsburg, there's a section where the scenery is not great after this and you'll hear and see the Thruway. There may be parking on Waldron Terrace near the dam which can be accessed by taking 7 Lakes Drive. Make a right on Waldron and drive until you see the signs 'Do not pass'; the dam is on you right.
Google Map of New York Whitewater