Rockerrider - You're welcome. Let me know if you have any other questions. We boondock a lot in the Cape Horn area past Lowman and before Stanley off Hwy 21. We Jeep a lot of that area too and now we have a small pop-up camper too to tow behind our Jeep to camp in backcountry area where our FW won't fit.
We've seen boondockers close to Hwy 21 off the Landmark Stanley Road. From there you could ATV down to Bruce Meadows, Dagger Falls, Bear Valley CG and beyond.
Also, you can boondock up at Stolle Meadows off the road to Warm Lake, east of Hwy 55. There's a free CG up there with a nice outhouse. A lot of ATV'ers up there too and although we've never taken our FW up there, we've seen quite a few. It would depend upon your comfort level in driving FS 474 from Warm Lake Road. Or you can camp at the South Fork of the Salmon River CG (again off of Warm Lake Rd), then take your ATV's up to Stolle Meadows.