I have a hard time figuring the size of glasses also. Best way I have found is to use oakleys measurements for lenses + nose bridge...to get an idea. I doubt it's a precise way to truly get a temple to temple measurement, but I think it gives an idea. Having said that, I'm sure someone here has all of the above and will chime in.
I definitely like the Gascan/Fuel Cell look, but have a bit wider of a head. Sounds like the Fuel Cells are my best bet from what I've read so far.
Is there another Oakley pair I should be looking at if I dig that Gascan/Fuel Cell look and have a head definitely on the above average size for width?
Welcome to the community here and the "Big Head Club". You need to try on the ones you're considering before investing, really. There are several pair I can wear that are comfortable and the same pair won't fit another "BH" because we're big in different areas. Fuel Cells are fine on me, for example, Det Cord, not so much.