I don't know if overnight parking is allowed at the 47 bridge. I'll be using the outfitter we have used in the past. Their website is http://www.santaferiver.com/
Basically we will launch 3 miles downriver which is past the portage area where the river is lowest. It will cost us 10 dollars to do that. Then we will have our jeep delivered to the HWY 47 pickup point on our departure day for 30 dollars. I will be happy to give anyone a ride back to their car at the outpost if they want to save the 30 bucks of transporting their vehicle down.
Hope that helps!