Here is a picture of Dave Lovitt's Sig Yak 18 B, about 80" span ( 2 meter +/-). If you could get a hold of him there would be a source of info. How to, I don't know other than to join the
RCSCALEBUILDER.COM forum and ask around there.
http://www.rcscalebuilder.com/forum/
Those scale guys might be able to help.