Access shouldn't be a problem. The old Scott timber property is usually accessible, and there are spurs off 20 that go up into the hills east of Hamilton. There are gates everywhere.
If you draw, the local RMEF folks might help you out- they have keys to maintain alot of elk habitat on the Nooksack.
Even if you have access to the main line, many spurs are 'no motorized vehicles', so expect to hoof-it anyway.