Sqwark2000, I've forwarded your post to an acquaintance who used to be a test pilot with Canadair for many years on the CL215. Hope he's able to answer your question.
I flew the Canso (PBY) for a short time in 1966. If it's any help, I remember the aircraft being nose heavy, but not overly so. On water takeoffs, because of the high thrust line, there would be an initial pitch down. You held the yoke full back until the nose rose as high as it would go, then eased forward to place the airplane in the planing attitude. You used elevator trim at any time in this maneuver to help with the stick forces.
If the CofG was outside the forward limits, water takeoffs were supposedly impossible, since the aircraft would not get on the step.
I've not seen this, but only heard of it. The aircraft has ample elevator authority, however. I've seen a picture of a Canso that had landed on a frozen lake. The snow was too deep for the nose wheel, so the pilot landed three point, on the mains and the rear step!