I haven't seen an RV specific model, but they do make higher quality dimmer switches at most hardware stores that claim to eliminate any noise/interference.
This may help:
Upgrade Dimmer Switch: With dimmer switches, you get what you pay for. Buzzing is more common with cheaper triac-based switches (a triac is the gizmo inside the switch that chops up the current). Better quality triac dimmers have an internal choke or filter that evens out the current and can reduce buzzing. Or, you can go for an even higher quality dimmer that uses an autotransformer, rather than a triac, which causes much less interruption to the current.
2013 Rockwood Mini 2503S
2011 Chevrolet Silverado 1500 5.3L