Boondocking is out in the boonies, away from people and civilization, so there are no campsites. It’s also dry camping, but you can also dry camp in a campground if you pass on any hu’s. I do it all the time. Most BLM land I’m aware of is lower elevations and I spend almost all of my time in mountain national forests. So I’ll let those who use BLM land speak to it.
In the nf’s, you can just drive back in on a forest road and set up about anywhere that looks good to you. There may be some restrictions, but they’re typically signed as you go in. Or you can ask at a local ranger station to play it safe. Actually, your rig is a bit big for that sort of camping, forest roads are usually rough, unimproved, narrow and heavily treed. But you could stay out close to the pavement as long as you have room to maneuver. If you want to go back one of those roads, unhitch and scout it out with the TV first. I’ve seen some people in very awkward positions as the road deteriorated and they couldn’t maneuver or turn around.
The few times I’ve used BLM land I treat it the same as nf land. Park where I want while watching for any signs or restrictions. I’ve been doing it for about 50 years with no issues at all.