It's all in the mirrors, Not much difference with lengths other than potential tail swing and you will need to take all the territory that's legally yours for turning.
For tail swing you first look in the opposite mirror of your turn to see what you could hit with the rear end if you turn sharp, tail swing is determined by how much distance is from your rear wheels to the bumper.The greater the distance the more tail swing. A 40' school bus has 10'+ beyond the rear wheels with a potential of a 3' tail swing. You need to drive forward as far as you can to make your turn allowing as much distance to get those rear duallies around the corner, we call it squaring the turn, 90 degree like turns. As you make your turn you watch the opposite mirror (ie right turn right mirror) to insure you clear curbs etc.
Practice brings improvement, it's much easier with an A than a C. With and A you have a clear view to pull your RV as forward as possible before starting your turn. You will see how close you are to things in front of you and can use your mirrors to see whats on either side.
Good Luck it's far easier than most realize.