Some truck stops have RV lanes with credit card accepting pumps. Normally I fill up at the larger service stations you see along the highways and haven't run into having to wait for the mini-van shopper. I've only filled up at one truck stop using the trucker pumps, I was able to use my credit card at the pump.
Most of the time I fill up when I'm unhitched from my 5th wheel; fill up the day before we leave or right after we arrive. Most trips we take require less than one tank to get to our destination. So it's just easier to fill up once we unhitch.