We do a lot of boondocking in the western states with our 40' - no tag. However, we pre-scout out the area in our Jeep before taking the motorhome.
We have never found a logging road suitable for us - narrow, steep, soft shoulders, minimal places to turn around. Many times the areas are scoured of trees, naturally, so it's not very scenic.
Forest Service roads & BLM areas are better suited for us and they lead to lakes and rivers. Again, we drive them first in our Jeep and we also check with the local ranger station for approved areas. We keep in mind 'what if it rains for days' - could we get out without getting stuck?
Our 40' doesn't limit us to places we prefer - lakes and rivers - but we definitely do our research. We typically only stay in one place for 3-12 days, then we're ready to move on. We're explorers, not sitters.
The easiest places are in the drier areas of the western states. The terrain will be more open and less rain to deal with. There are plenty of excellent boondocking spots for big rigs so don't let that deter you. You'll need to adhere to the rules of how long you can stay in one area and most likely, it won't be for a whole season. You do need to keep in mind your ground clearance - and it's not much. You need a good basic road to begin with. We don't do boulder hopping. :) Good luck!