Sounds like a fun little competition! IMO the triangular gussets in the wing would not need to be used. You could save a few grams there. A narrow piece of 1/32 balsa sheet could be used on the leading and trailing edges if you you are concerned about the wing "racking". The covering should hold/keep that from happening though.
I can see you building at least several dozen of these planes trying to find the right combination.
I'll bet you and your friends will have a ball with this.
Ken