Fuel islands are for fueling, and rudeness is rude no matter what you drive. I know people like to "Park" at the local gas station when fueling up....make a trip inside for road snacks. Doesn't help that many offer fast foods, etc... The truck fuel island is not the place to do this.
Grap a cup of coffee while paying for fuel...sure, that is not a problem. Make a trip to the Taco Bell, or McD's....BAD IDEA.
Gas station people don't care that you need more space, they only care about putting in their $10.00 of gas and getting a MONSTER drink.
The truckers understand that YOU are just looking for space, like they are. When I drove Rigs I really watched RVer's in the "truck" lot....make sure they know what they are doing. You are the small one back there....we watch out for the little guy who might disappear in our field of view.