I've turned the corner once. Did it with an outfitter. MF was at 2.5 ft. in early July. 6 days on each river & they resupply at Cache Bar. While the guides were doing the resupply, we were at the Salmon River Lodge doing laundry & relaxing.
As others have said. Your last day on the MF into Corn Creek will be a LONG day. Some of the trickiest rapids on the MF are in that last section. Then you've got Cramer on the MS to deal with. Are all of your group doing both rivers? Having new folks join you at Corn Creek would make life a lot easier with a resupply. All of this may be mute depending on how your permits line up. You will likely be forced to chill at Corn Creek of awhile.
It's such a great trip. If you have the time, don't rush it.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb