I pull a 37 ft. travel trailer with my gas 2500HD and have the same problem with gas stations. I am near 58 ft. long connected and stations are just not accommodating to that length usually. I start looking at 1/2 tank and take any opportunity to fill up when I come across it, even at 1/4 tank.
Looking at the map you might be better off just staying on 55. Navigating Memphis is usually not that terrible just stay away from rush hour times. Been thru many times on 40 with only one back up issue due to a wreck. When time is not an issue we tend to take secondary roads and enjoy it more. Gas is usually easier to find some place I can get into also.