I agree on the Class IV put-in. A long steep slide for the boat with a LONG rope. Just be grateful it is the put-in, NOT the take-out. The long Blue float goes to the Trough road. There is a shorter run of the canyon only, with a State access take-out above the bridge on river left only a few miles downstream from the put-in. I forget the name of the road off the highway, but it is the left turn (west) into the first housing development north of the reservoir, and just follow to the river and cross the bridge. Parking spaces on left.
Additional comment - I just went to Eddy Flower to see what you were referring to. The put-in trail reviewed is NOT the one we mostly use. That one is higher up, and some people want the extra 100 yards of run. That is NOT accessable to rafts. Instead, follow the paved road down past the dam to the very end. At the parking lot, there is a little dirt road to the left that trailered rafts can be backed down to the top of the long put-in slope. If you put-in in the morning, there should be others there to show you the way. Have fun!