Wow, that Phaeton should do well with a 72cc engine.
Here was a helpful site that I used a lot:
8 Ft Wingspan Coroplast RC Piper Cub Flown by 25cc Weed Trimmer: 27 Steps (with Pictures)
I have the bottom wing incidence adjusted. Now all I need to do is remount the top wing with no stagger. That will put the CG at the right point without adding any more weight.
The weight is 17 lbs, which makes the wing loading a little less than the 8' Coroplast Cub in the article above.