I enlarged one of the photo's from the manual (ex GP website) and it appears that the entire side of the fin is sheeted - which is what I have now done.

Will post photo's once glue dries.

Spoke toLHS today about the engine choice, his comments were why along the lines of "Why go for the FG-20 when the FA 125 is lighter and has more power, not to mention 30% cheaper", so made up my mind to get the FA 125. Also means I won't have to carry two fuel cans when I go to the field....