The Oregon claims I know are going to be pretty high water in March, especially with the rains we have had. Those are the Quartzville group and the Cat and Paradise (nasty to get to) down out of Cottage Grove, probably even still snow on the last two.. Best conditions will probably be from the Sacramento area south, but don't know the claims down there.
Contact the chapter contacts listed in the mag or P&S that are in the route you are following to get some pointers and help. Worth a few phone calls, and you might hit a chapter outing.