The Mojave Rd will send you towards Laughlin, NV. Not Vegas. You'd be on the Mojave Preserve which is very scenic with plenty of points of interest but theres nothing hardcore about the trail. I just ran a 85 mile section of it going to Laughlin a few weeks ago.
If you want a long off road drive I'd suggest starting in Lucerne Valley and cutting across Johnson Valley diagonally from the Southwest to the Northeast. I've encountered some good off roading out there. From there you'd end up in the small town of Ludlow on the I-40. From Ludlow you could go directly North and pickup the Mojave Trail going East for a bit. Then when you hit Kelbaber Rd you could cut south a few miles and pick up Aiken Mine Rd. A point of interest on the Aiken Mine Rd is the Lava Tubes. Once your at the old mine you continue east inline with where you entered the mine ( North side of the gravelly section). That'll take you through a little old ranch and through a thick Joshua Tree forest. Where you come out on Cima Rd you can see I-15 to your left. Theres a memorial near there and some awesome looking rock formations.
From there to continue off road I'd need to look at the maps for you. You can dry camp anywhere out there but if you want something with actual campgrounds let me know and I can change this route around some for you.
Crossing Johnson Valley the way Im talking about, completely offroad, will be a long day. At least the way I went it was.
I got in to some pretty gnarly off roading, I could of bypassed the hard stuff and shortening the trip some but we were having to much fun.
This route, you won't see many, if any people except for when you pull in to Ludlow. Ludlow would be a fuel stop. From there if you needed another fuel stop you'd have to cut north to Baker when you come out on Kelbaker Rd. Then you could just double back and pick up Aiken Mine Rd and continue on.