Dude, PLEASE check out the link to Person Man I included, especially his list of links a little bit down the page. It will make your life much easier, and it will make ours as well.
For example, there's a link all about gaining more reach. Off the top of my head, I can get 20 feet while being medium: spiked chain + aberrant blood + inhuman reach. With colossal that should be what, 60 feet? I've never made a character that big before.
I would probably also use those tricks to get my base damage up to the stratosphere using unarmed strike or size increasing shenanigans, but that's just me. The idea is to make each one of those AoOs major punishment.
In the Epic Level Handbook there's some crazy bracers, I think, that increase your size. If you've got cash to burn, they are something I always drooled over.