I think EZ Pour has what you want.
I'll second that. I bought a 1.5 gallon EZ Pour can to use for spare fuel on my motorcycle, and fell in love with it. I bought another for the chainsaw. (premix) The 2.5 gallon can is about the biggest that I can easily handle and pour from with the included spout though. The 5 gallon cans are a bit big to handle with one hand and open the spout with the other, but they offer a cap to replace the spout, and they are built very sturdy. And made right here in the USA, which is always nice.
You also can't really fuel a vehicle with them, but that's the case with any CARB approved spout. The sell an extension, but I prefer to use a jingler siphon.
On another note, I've seen a few of the Scepter red cans in this thread sitting in standard metal military carriers. They're evidently a tight fit, but they will go. Perhaps a little heat and hot water would help??
Does make you wonder why they decided to make the cans a tiny bit wider... Probably to keep them from falling over, since the cap is likely not terribly leak proof compared to a Mil can.