That's good to know, Rahn. I wasn't sure it would work that far back. One problem with that is the storage/cooler space it would take up in that position.
I have decided to go with something I have used on other boats that works pretty well:http://www.coolibar.com/04106.html
If you shave it down some, you can fit the handle of one of these into some PVC and insert it into the scupper holes near the back crossbar, then strap the PVC to the crossbar. It will stay put well and can be removed easily and switched to the other scupper hole to change tacks or to shield the sun if it's on the other side. I'll post up on it when it comes in. These umbrellas have been back ordered for a while now. They also go by Gustbuster Sunblok. I used it on a couple of different boats, including a Hobie Revolution and they really keep things more comfortable.