OK, well the suspense was killing me, so I had to call Grant
Thanks for the number, Irishrover.
Grant's really nice... he basically said what Irishrover was saying about fees and such. I asked about Dodge to Oxbow for floating down in an IK (I asked about taking out at Gordon Creek to avoid the parking fees but he pretty much just does the main parks).
He'll get the description of your vehicle and where it will be at your put-in. You stash the keys somewhere (a little unsettling) and let him know where. He'll pick up the rig and drive it down to your takeout and stash the keys somewhere again. You pay the parking.
I gathered that adjacent parks are about $20. If you go a little further, it's $30. I think he said Dodge to Dabney was $30. Not sure how much if you wanted to float all the way down to Lewis and Clark.. maybe something around there though, but I guess it would depend on where you put in too.