Lucerne to Barstow is kind of twisty, but nothing that's a big deal. I've towed it several times without incident. I honestly don't remember if it was rough or not, so the road must not have been an issue.
Victorville to Barstow would be backtracking quite a bit, for no reason.
Come to think of it, I normally go through Victorville because I've been boondocking and need to stock up on supplies. The route through Victorville goes right past Walmart and a big grocery store. There's an RV park, too, that will let you dump tanks and fill up with fresh water and propane.