I put 3 kiddos on long road trips in the back seat of my F250 crew cab.
No problem. Plenty of room for all their DVDs, books and stuff.
The center section has the arm rest that folds into the back of the seat, doesn't bother anybody. In fact, they didn't even realize it was there the first road trip.
I looked at the Mega Cab when I was shopping. Looked nice, but it was pricey, mostly because it was not available in the configuration I wanted. Most Mega Cabs were all fancy luxury models, which I had no need for or wanted to pay for.
Plus, it eats up the payload of the truck like crazy.