We tend to go up a size on Pampers with the weight ranges, but my son is long and skinny. We've been in size 3 for a looooooong time. That being said, I long ago switched to Pampers Extra Protection (aka "night/overnight diapers") for nights. I originally went only a size up and now that he's bigger, I go two sizes up. They're huge on him, but he will pee out of the size 4s. You can also try just getting your normal diapers (though Baby Dry are better than Cruisers for large quantity pee containment, Luvs are as well) in a bigger size and using those at night only. That way, you can always use any leftover ones when he bumps up a diaper size. If they're not enough to contain it all, try the night diapers.
I've also recently tried the Huggies version of night diapers. They work fine for us, but are more expensive per diaper. They're actually cheaper per box, but their box has about 20 less diapers than the Pampers version and is about $5 cheaper. The Huggies version works fine for us, but I've heard otherwise from other Pampers moms.