While I have never camped there, I know of folks with a 40' DP who have done so. The roads into that area are two lane and not very wide but you should have no problems if you are careful.
It is a beautiful area.
2007 Country Coach Allure Siskiyou Summit, sold/traded Nov. 2018.
2019 Grand Designs 384GK-R 5th wheel. Glen Allen, VA