X2 on all the above. There's no problem finding fuel at RV-friendly stations on the interstates. When I get down to about 1/2 tank I start looking. In been my experience there has always been a fueling station (truck stop or travel center) somewhere down the road before I reach 1/4 tank.
When using secondary roads you have to be a little more judicious. If running low on fuel and a smaller station is your only choice you may have to unhitch nearby in order to safely reach the pumps. I've had to do that on occasion but it's very rare.
Of course, you can carry extra fuel in a 5 gallon container just in case. I used to do that when I first bought my truck/fiver but found that I really didn't need it (not all stations offered ULSD fuel in the early days, which is required in my truck). Today, I have no trouble finding the right fuel.