Good luck with the new camper. We upgraded to one about that size two years ago. Overall, it has been great. It has reduced the number of campsite options a bit but we are still able to find a spot in most parks.
For fueling, here is what we try to do. We learned after a try or two that regular gas stations are often not a great option when towing a long trailer. As others have mentioned, fill the tanks before you hitch up if possible.
When on the road, stop at RV friendly stations rather than regular gas stations. For example, when we travel on I95, there are Flying J stations spaced out about every 200 miles. They have two RV pumps separate from the regular pumps. As a bonus, we get a 5 cent per gallon discount with our Good Sam card.
When a Flying J isn't available, we have sometimes used the truck pumps. Note that their pumps are a bit different but still work. If you are using diesel, that is an option to consider.
Hope that helps.