I didn't mean to discourage you. Actually that may be somewhat unique, and I'll be intrested in how it runs. There are lots of single motor ones out there. Everything else you are doing sounds good so keep going. I hope you have a video camera. . The cheapest strut I know of is the one on OSE, the replacement for the SV27.

http://cgi.ebay.com/rudder-stinger-4...item1e58b487fe
this is a 4mm setup that comes with a rudder won't work with your 3/16 (0.187) or 4.76mm. You may be able to contact the seller and get two struts and a rudder if you can make 4mm work. I feel your pain.