Feel your pain. I choose a station based on price. Filling 2 tanks a time it makes a difference. If I can time the fill without the trailer that is great but it does not always work that way.
It sure is a nuisance to pull into a station & find a gas vehicle at the outside island, which usually is the one with the diesel. I think most of them are plain old oblivious to the fact that the only diesel is right there & the smokers have nowhere else to go. Some gassers use that island because it is the easiest & they are lazy. Some are aware but simply do not care about anyone else.
Whatcha gonna do? We diesel burners are stuck with them.
If I have the trailer on the back I will pull up within inches of the offending gasser in order to be out of the way as much as possible for those trying to get around behind me. Sometimes this will get dirty looks from the gasser followed by an explanation of why I am there, why I can't use another pump & why they are the cause of a hold up for others. That is when the lightbulb usually comes on. Hopefully yet another gasser at the diesel island has been educated.