Your freind is wrong. With a high enough tail volume the CG could be on the wing's trailing edge or even further back. Mind you by that time the plane would look more like a tandem wing design....

I didn't bother to look at all the other numbers. I'm just not big on math until the general arrangement drawing is done and then I run some numbers to justify what I want the design to look like rather than do the numbers at the beginning. A 3 view sketch with the dimensions would make it much easier to see all the numbers at a glance and determine how they all fit together. One decision affects a lot of others and seeing a small scale drawing with the dimensions makes it easier to see if it looks about right before diving into the math for details. For example, off the top of my head your stabilizer area seems a little small at around .22 sq ft with 2.7 sq ft of wing. A longer tail can compensate for that but it implies such a long tail that the model will look rather ungainly and the tail boom may come out rather weak unless it's too heavy. A few years back gliders typically had spans that were 2.5 times the fuselage length. More recently more designers are going with spans that are 1.8 to 2.0 times the fuselage length. I like the newer numbers as they produce models that are more responsive to rudder-elevator setups and tend to be more stable in the thermal turns. At least that's what I've found with a couple I've flown with longer tail moments. But it's easy to end up with something really odd looking if you take this trend to extremes. Again a general 3 view sketch done to scale (CAD?) will help with this and help us to help you.

The case where your numbers call for an 80 degree deflection of your stabilator clearly shows that you've got some serious issues or you asked for an amount of control authourity that is far more in keeping with a 3D aerobatic design than for a soaring model. The only way the equation would call for that is if the stabilizer is MUCH too small or you put a decimal in the wrong place somewhere. No sailplane would ever need that amount of deflection for normal flying. 8 degrees would be more like it and very typical.