Well you can take your pick from several, although I doubt anybody goes to the Ferry and all the way into Diamond just to drop and pick up groovers alone.
Canyon REO and PRO are the two biggest outfitters in this category.. But Moenkopi and Cieba are in the full (or near full) service business as well.
One of these companies may be able to help you work out a plan. Google them and start reading and calling.
Join Grand Canyon Private Boaters Association at Grand Canyon Private Boaters Association. click on "Join", and support active, ongoing private boater representation on Grand Canyon issues. And follow GC issues on http://groups.yahoo.com/group/gcpba/messages