Allen Basin Reservoir is roughly 1 mile from Crosho Lake. The only way to access this reservoir is by using trail #1181 and either hiking in, or using an ATV/dirtbike. You can not drive back to this reservoir.
There are roughly 6-8 dispersed camp spots on the road towards Allen Basin Reservoir. We camped at this spot for 3 days, and 2 nights and loved it! Plenty of coverage from the close by trees, access to the trail directly behind our camp spot, and there was a make shift bench made from a fallen tree! We highly recommend this spot, but do recommend driving a 4x4 vehicle to get here, and don't forget the bug spray!