RE: Sig Sealane Incidence ??
You must remember that the Pondhopper was originally designed for a 40 engine so you are probably using a lot more power than was originally envisioned. I would suggest,
1. going easy on the throttle when accelerating; 2. increasing your up elevator throw to counter the nose down pitching, 3. using lots of exponential (-80%) to soften the elevator when airborne. This should be a good start to good flying.
I don't think upthrust will help much for the problem you are describing but, all incidence and thrust measurements should be measured from a common datum line which is usually parallel to the stab. Since seaplanes have wierd thrust arrangements because of the high thrust line I would make my measurements relative to some easilly found datum like the top of the fuselage side. If you consider the datum line to be 0 degrees then record the other angles relative to that; ie: wing +2, stab 0, engine +4 or whatever.
This should help sort it out.
Peter