If a high wing plane is ok you could build the Vailly Aviation 1/5 scale Bird Dog.
http://www.vaillyaviation.com/Intro.html
1/5 Scale
Wingspan ............... 86.5 inches ........... Wing Area ................ 1003 sq.inches
Overall Length .......... 58 inches ........... Weight ...................... 11 - 14 Lbs
Engine ..................... Zenoah G-23, or equiv.