Awesome work! Very cool that you went out and made some rudders to tool around with in light air. Also very cool that you bought another G-Cat- a 5.0 MkII no less. I'd be interested in hearing your comparison between the MkI and MkII when you've had more time sailing them.

In very light winds, going wing-and-wind is perfectly acceptable. My only "critique" is that you're sitting too far aft. You want to be sitting up by the mast beam to help balance the boat- the transoms should never be in the water (especially the case on a GCat with their tiny transoms). Investing in a telescoping tiller (Arriba Hot-stick or similar) will help a lot with positioning yourself on the boat, especially when you install a trapeze system and find youself trapezing ahead of the mast.