I once pulled into a large and very busy gas station near Rawlins, Wyoming with my 30' fifth wheel - because it had cheap fuel. I quickly realized that the pumps were situated in such a way that I couldn't pull up to them. Then, I realized that there was only one entrance, and the only way to get out was to back up through cars and curves about 100 feet to the busy street. Thanks to a few very nice people who helped my wife direct traffic, it only took about 15 minutes. A nearby gas station was a little more expensive - but was RV friendly.
Now - especially when travelling through less populated areas - I plan my route and gas stops before leaving home. I use the internet and Gas Buddy to find gas stations, and then look at them using street view on Google Earth.
This still isn't foolproof, but works most of the time.
http://rvfriendlygas.com/ looks as though it will be a great planning tool, but needs lots more input from the RV community.