Windshield size for bonnie

[Elguapo]

I'm getting beaten up by the wind on the southern calif freeways and am searching for a suitable and affordable windshield for my Bonneville. I don't want to ruin the look of the bike but want to make longer rides more comfortable. The triumph website has three sizes but I've never ridden with a shield before and have no idea how useful the smaller shields are. Anybody have experience with this?

Thanks

P.S. Anybody else wish their bonnie had an extra gear? I'm at 5000 rpm's at 75-80 mph!