The settings I used were to set the shutter speed to 1/4000 sec. -- as fast as possible. I also had all of my ND filters ready and went from stacking a 1.2 and 0.9 (7-stops) to no filter, depending on the the cloud cover. The dual iso setting was 100/1600. I also had the intervalometer running so it was taking a shot every 10 seconds. I kept my hand on the F-stop ring and adjusted so that I could see something in the LiveView display. Not very scientific or well thought out but something I learned when I was making a living in photography is that the only thing that matters is getting the shot so bracket the hell out of it!
This is a shot
without dual iso. The sun is pretty much burned out and this is as far as I could stretch the image.

If I were to do this again I'd seriously consider getting a 3.0 (10 stopper) ND filter or maybe even a 5.0 Solar Eclipse (16.5 stop) filter. Stacking filters and shooting straight into the sun is an invitation for some weird flare patterns.
This is what that dual iso shot on
post 1761 looks like before processing.

Not very impressive, is it? That dreaded costal marine layer really helped the shot and so did dual iso!