My SUV gets the same MPG, if not a little less and has only a 26 gallon tank. Really only 20 are effective. Giving me 160 mile range if I assume 8mpg.
Previous trips have resulted in stress of finding a station when we get near 1/4 tank and at times when we finally found one...it was in the middle of no where. Or, in a couple cases, there was no way I was getting in and out easily with the trailer.
This last summer, for the first time ever, I planned out every gas stop for my entire trip while towing. For a 3 week trip, it took me 5 nights or about 15 hours.
I used Garmin Basecamp and Google Maps to plot and research every single station.
Knowing EXACTLY when and where the next stop was before I even start the engine made for one heck of a relaxing drive for the whole family.
If you have a small gas tank, I highly recommend trying this.
But if you have a 30-40 gallon gas tank, then not so much unless you're trying to extend you run time as far as possible allowing the tank to hit 1/4 or less before worrying about stopping.
Oh. I have always carried 5 gallons of fuel along as well. Never had to use it but it also never reduced my stress level to find a station either.