Two of us recently went that route with our RVs.
There is a bypass around most of Boulder City now which will save you some time. Your real hangup will be Hoover dam. All traffic stops for pedestrians and if you get to the dam anytime during the day, traffic could be backed up for a couple miles.
You will also have to go through an inspection before crossing the dam - open a few compartments, etc.
Once you hit I-515, it is smooth sailing - according to time of day of course.