Two interesting points here.
I don't know what you road trip guys are doing different than me, but I can't go...MAYBE.....2.5-3hrs in the car before someone in the family needs to get out for something. Mom has to pee, kids need to pee, I need to pee, dog starts barking, kids start arguing. Never have I been able to get more than about 200-250miles between stops for some reason or another. I fought it for a few road trips, tied myself up in knots in anxiety and being pissed off we "weren't' making good time". These last couple times I've learned to just budget for it. Just expect we're going to get out and goof off for some reason or another a few more times than I would if I was travelling alone, or just with a buddy. My stress has dropped and my trips have been arguably more enjoyable. Just embrace the chaos and live through it......So, for me anyway, a large tank is mostly a waste of space/weight/etc. I wouldn't turn it down, but I'm not gonna seek it out either.
Towing is pretty obvious use case for the larger tank too.
I work right next door to a Sams club. Like, I could see the pumps from my office window the first few years I worked here. I've learned the best time to get fuel is before 8am on the way into work. You can zip right in, grab fuel, and be on your way without waiting in line. Any other time it's a case study in how to NOT do traffic control. People in/out all different directions, long waits, and generally more stress than the cost savings is worth (unless you have one of those absurdly large tanks sitting on E, then it might be worth it). I worked through the math awhile back, and I think I need to have lke 16 tanks of fuel before the membership price breaks even, and anything after that is a savings.