Dash/seat protection

Use whatever you use in your cars.

I use 303 Protectant on the dash to protect it.

When it is not being driven and parked/stored I use a Windshield Cover to shield it from the elements. With the over hang on a Class C the seats don't get a lot of exposure

Get a snap on exterior shade. They last forever.

I use automobile products meant for protecting interior materials, primarily purchased at Walmart. We have used Armor All and Scotchgard in the past as well other other similar products, they have a decent RV section where they have RV specific products if preferred. Are they any better than standard automobile protection products, that is subjective, one thing for certain, if it states for RV use on the bottle it will be more expensive.

Same stuff you’d use in cars. RVs aren’t special in this regard.
Consider a windshield shade too.