You will be fine in mid July with the rigs you describe. Actually when it gets real low latter a big raft lightly loaded is even better than a smaller raft on the GR because the issue is shallow water over wide gravel bars, and the greater surface area of a bigger boat is key for floating as shallow as possible. Regardless mid July isn't really that low. Even in a fairly dry year, it is typically over 1000 cfs then, no problemo. We are going the next week after you. I would recommend at least 3 nights on river from Minam to Powwatka. You can do it in 2 nights then, but 3 is better. Use Grant and Lottie at Minam River Raft Rental and Shuttle to move your rig. Their new place is on the East side of the river at the Motel Property. Good peeps.