I've ran from garrison to the beacon, 7 miles west of Inidan hills, and back a few times with the new rig which is an 80 mile round trip and it's pretty much spot on a 30 gal run clipping along around 50-52 mph & 4500 rpm. That's 2.66 mpg. It's 16 miles further to get to shell. That'd be a 42 gallon round trip leaving 20 gallons to spare. Realistic range is about a 160 miles. That said, in general the arm is well within range for most of the pro's without refueling depending how hard they run. I could probably get to flag and back but it'd be tight, I'd have to watch my speed a little.
If I back it off to 35 mph, 3.5-3.6 mpg is about what it settles in at. With that said, on a 120 mile round trip, the difference of running 35 mph vs 50 mph is an entire hour of fishing. Considering most can run 60-70 mph at WOT (conditions allowing), clipping along at 65 mph vs 35 mph is going to add more than 90 minutes to your fishing time. The questions actually becomes is it worth a 1/2 hour refuel time to run WOT versus 50 and be able to make it with out a refuel. turns into the same amount of fishing time but you might beat some one conserving fuel to the spot.
Lots of things considered by these pros when making these long runs.