I will scope out the station before pulling in - even if means holding up some traffic for a few seconds. Also, I have had to back out of a station on more than one occasion. When that happens, my wife will act as spotter and stop traffic if necessary. I have even asked a fellow traveller to help me if my wife was not along.
Generally it is not a problem and if you try to get the outside pumps or stations that have parallel pumps to the road (getting rarer!) you will be ok. Beware of stations that have the pumps perpendicular to the station and close to it that allow patrons to park in front of the building. That is the situation that would most likely make you have to back out or wait for someone to move. In cases like that, I will not pull in unless the end pump is available.
It is not something that would require an app or something like that to help you out. Of course, truck stops are always an option but they are usually quite dirty.
Barney
2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine