Almost all RV's tend to wander from cross-winds, passing trucks, dips in the road surface, etc. You can improve things with proper air pressure, and wheel alignment with your camping , etc., stuff on board fresh water tank and holding tanks about 1/2 full. Some RV owners invest in stabilizer bars, special shocks, airbags, and special alignment settings, etc. and some claim much better handling after the upgrades. Most Class C's have a harsh ride on weather and heavy truck-damaged rough interstate highway surfaces. The rear springs on many RV's are quite stiff to handle heavy cargo in the rear.
You may learn to "live with" typical handling and harsh ride issues. We have always taken frequent rest stops to stretch, walk around and sit on solid ground to calm nerves from driving on rough roads. Try making reservations or finding an RV park in afternoon time to settle down for the night, avoid "no vacancy" problems and anxiety of trying to find a place to park at night.
Enjoy the ride, taking secondary asphalt paved roads with better scenery when practical. Try to keep speeds around 55mph for best fuel economy and more relaxed driving. Use lower gear on downgrades to save your brakes. Pull out when safe to let the parade pass, ignore "hand gestures" from passing cars. Change lanes carefully and plan ahead for off ramps and merges using your GPS.