For what it's worth, we did a Middle-Main combo last June after a number of years of coveting one. Launched June 13 at Boundary Creek (3.3 feet) and got to Corn Creek on June 20 (2.2 feet at Corn Creek). There were only three of us on the Middle Fork, met by seven others at Corn Creek. The friends meeting us at Corn Creek brought in resupplies, and we all spent that night at Corn Creek Campground before heading downriver the next morning. It was a superb trip, 16 days for the 180 miles, lots and lots of rain, mellow water levels. Definitely worth doing a combo, and taking as many days as possible. If you get serious about doing it and have any questions about resupply logistics, I learned a bunch of stuff would be glad to share via PM.