Yes, with carefull planning and preparation you can have an enjoyable RV trip with an autistic child. Most RV Parks, National and state Parks are suitable for people-with-disabilities.
Some aspects of the RV travel may help the child e.g. he/she can be occupied productively at the dining table in the RV area with games. You can also take lunch stops at any nice place as you travel.
On the downside please realize that RV drives about 10-15 miles/hour slower than cars on the same road, please factor this time in your itenary.
RV is noisier than a car, you can mitigate this by bring a good quality portable speaker and play your own music.
Please also refer to this old TripAdvisor thread on travelling with an autistic child https://www.tripadvisor.com/ShowTopic-g1-i12567-k5482066-West_coast_usa_road_trip_with_a_disabled_child-Road_Trips.html