And here is a simple way to find mean or average chord to measure back from for your CG. It is called mid span averaging and works quite well with any monoplane wing that is single tapered, leading edge or trailing edge as well as a double tapered wing, heck even with an elliptical wing.
All you need to do is to measure the distance between the leading and trailing edges out half way between the fuselage and the wing tip. This will be your mean (or averaged) aerodynamic chord for weight and balance purposes. Now if you want to balance at 25% mac (a figure that I definitely agree with for that airplane for first flights) then all that is needed is to divide that measurement out there half way between the fuse and wing tip by four. And this sum is measured back from the leading edge out at that half way point then just projected straight into the fuselage side for balance purposes.
John