The Au Sable system in the Grayling area is mostly fishable without a boat. There a numerous places to access the river also. If I had limited time to fish the night before and was staying at Gates Lodge I would fish right there. From town I would go upstream on M72 to keystone landing which is easily found and waded. If you arrive early enough in the day you can take the road a little farther east to Smith's bridge and follow the signs for the Mason Tract. This is a beautiful place with lots of access to the South Branch.