When we were fulltime we had a 40' Monaco and towed a Saturn Vue and used truck washes when available. They generally charge by the foot and will wash the toad as well. The two issues I had with truck washes was location (generally on major interstates) and waiting in line behind one or more trucks. It generally takes 30 - 40 minutes to clean each vehicle so have something to read. If you use a truck wash, tell them that you do not want chemicals used on the wheels. You can find locations on internet sites such as Blue Beacon Truck Wash, Truck-O-Mat and other trucker sites. We did carry our own equipment and washed at campgrounds when allowed. Costs ranged from $5.00 to $20.00 depending on the campground.
Now I wash our 2910 after each trip and get it restocked for the next trip. If I want to wash the RV while on the road I have a bucket, brush with extendable pole, car wash soap, glass cleaner and microfibers. I carry an extra hose as well.
RVs always run better when clean....