Before you start spending money on modifications, I would suggest weighing the coach when loaded fro travel and then adjust tire pressures based on the axle loads. The tire manufacturer should have a chart available that will provide the correct tire pressure for the load. Over or under inflation can lead to handling issues.
Next while loaded, get the front end cehcked at a good truck suspension shop.
If this does not help, next issue will be what modifications to try. Depending on the chassis, you may need stiffer anti-roll bars, track bars, panhard bars or HD shocks.
But fiirst get tire pressure correct and the front end checked.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot