The Bushman is right around a 4" brim.

I find oilskin hats to be the same as wearing a sauna on my head....felt is much cooler for me.

For a canvas hat nothing beats a Tilley. I have a half dozen Filson tin and shelter cloth hats....never wear any of them as they are just too hot and not comfortable at all.

Also I do not consider a Boonie to be a hat.