Well, I did it. I took out the three torx head screws that are exposed when you open the filler door. This allows you to move the thing around enough to loosen the hose clamp that attaches the rubber hose to the bottom of the filler neck. Unfortunately, the hose was severely stuck, and I wound up removing the hose at the tank. It came off the tank easily, but then you have to feed the hose back through the frame. Not fun, but possible. The vent line is clipped to the filler neck with a plasic clamp and there is a ground strap from the filler neck over to the body. It simply pushes over the sheet metal edge. With all this done you can work the whole assembly out the bottom. Once it was out I drilled nearly adjoining holes all the way around the edge of the restriction, cut it out, and used a small drum sander in a drill to clean it up. Washed the crud out of it and put it back in. It looks like it was built that way. You'd have to be looking for it to notice the mod.

Haven't filled yet, but here's a pic. Click for larger.