Welcome to the forum. My rig is a 40' fifth wheel towed by GMC 1 ton dually diesel averaging 10 to 11 mpg towing weighing in around 23400 lbs. Diesel is north Alabama runs from $3.59 to $3.79 a gallon, a little less expensive than yours. Most of our trips are within 200 miles of home, prefer to relax than drive long distances. From the pictures I've seen of yourRVs they seem more modern looking and brighter, which I like and wish the US would embrace.
We welcome you to the US, its a beautiful country with a lot to see and do. Let us know what questions you have, this a great sight for information.
Happy Camping
Randy