I used to live in Grants Pass and fished this every year..... it varies each year like all fisheries, but generally speaking we always had the bumper boat, catch lots of fish last two weeks of august through the first couple weeks of Sept. There is a great place to stay right there with a boat ramp, and tackle shop.. it used to be called Jot's Landing... call them, and they will give you the best report on the fishing, and it still might not be to late to reserve a room.
Good Luck and have fun!!!
We used to run a mooching rig, use a bait threader up through a whole hearing the front hook is a slider and the rea hook is on a loop, so it can be removed for threading.... rear hook was a treble, back then.... check the legality....