https://youtu.be/70b9cYMILFo?list=UUvajm0pYeG7PvspskjQLq9A
This is a "rough scale" Corsair I scratch built for 1 cc power. It uses a 4.2 x 4 prop.
It uses a 1/4" thick solid balsa wing and the model weighs about a pound IIRC.
For a .25 sized version, you could base the model on a 1 inch thick wing for a balance between strength and low drag.