How long to learn to drive a Class A

Remember, that a motorhome is a large slab-sided box. Nothing like the PU you have been driving. The air currents and any wind will affect the motorhome much more than any auto/truck-sized vehicle. Some of the "sway and playing" you are experiencing is not actually there but since you are sitting higher it will seem to be a bigger problems. It is somewhat in the same region as how much faster you will seem to be going in any vehicle the closer you are to the pavement. All that having been said any motorhome has a higher center of gravity than any car/truck vehicle. Try riding along while someone else drives the motorhome and see what your perceptions are. I think that you are worrying more about perception than reality.