RE: sig hog bipe CG problems
How do you have to hold the controls? Are you holding a lot of 'up' elevator just to sustain level flight? You may not be 'tail heavy', but underpowered, and flying too slowly. Usually, if the airplane's not flying well, and tends to wallow around tail-low, people will say it's "tail heavy". Not so. That usually means an airspeed problem. If the model was 'tail heavy', it would tend to be very sensitive on the pitch axis.
You didn't say what propeller you're using, and what RPM the engine's turning. If you have a prop with too little pitch, and the engine's rich enough that the RPM isn't where it belongs, then you will not get enough airspeed to get the model to fly well. A 13 x 8 APC prop should turn in the mid- to high-9,000's, and should provide plenty of airspeed to fly the airplane well.
One way to check balance when the airplane's flyable, is to take the model up high and put it into a dive. Release the controls. If the model tends to pull up, then it's nose-heavy. If it tends to steepen the dive, it's tail-heavy. If it only changes a moderate amount, it's about right.