You guys were correct - I didn't understand the significance of "async" in the compatibility guide.
To be safe, I first downloaded and installed the latest version of the firmware on the 6805E.
I downloaded the driver from here: https://my.vmware.com/group/vmware/details?productId=285&downloadGroup=DT-ESXI51-PMC-SIERRA-AACRAID-...
I then loaded that driver post-installation and confirmed it could see my raid.
Next, I went to http://www.v-front.de/p/esxi-customizer.html to create a customized install ISO with that driver. I used the .vib image from the drive zip I downloaded. When I used the new customized ISO, my array showed up perfectly.
Thanks again for all your help!