Contact a truck driving school or rent a U-Haul, Budget, Ryder, etc.. I may be a little more expensive, but, start with a small truck like a box van. Then when you are comfortable with it, rent the next bigger one and so on, until you get to the size of the coach you are thinking of purchasing.
2010 Ram 3500, Crew Cab, Long bed, 4 x 4,Dually, Lights & Siren!
I really do think that some prior training is a good idea, just look out on the roads to prove it. If you are an experienced driver, it should be no problem, just get someone to go over the features of the rig, and understand them. Use common sense, and be aware of the limitations of what you are driving. If you are buying where you are, get the dealer to take you out on the road for a trial, if they won't do that, find another dealer.