I have seen several Lakers flying, and they were all very well-mannered. None had any problem getting airborne.

I don't think the original hull design or your v-bottom modification would have any problem breaking suction. Model planes don't seem to have a problem with that, anyway.

It would seem that you either have a technique problem, or something unique to your plane.

Technique: Use FULL UP elevator to taxi, and when you initially start your takeoff run. As soon as it pops up on the step, neutralize the elevator, let the plane gain speed, then gently apply back pressure to lift the plane off the water.

How did you install your water rudder? Is it oversized? Can it kick up? If the water rudder sticks into the water more than 1/2" when you taxi, it is too big unless it retracts or kicks up. Water rudders are for taxiing. ONLY. If it is in the water when the plane is on step, it can keep you from reaching takeoff speed. If it dips in the water when you rotate for takeoff, it can push the nose back down.

If your plane is too heavy, it could be submarining when you first apply power. When you first start to accelerate, some of the water is pushed forward. If this comes back over the nose, it causes drag, loss of hull lift , and loss of engine thrust when it slows down the prop. The cure for this, if it's not too severe, is to add chines(spray rails) to the edges of your hull. Make them from triangle stock. They provide more lift by deflecting the horizontally-flowing water down. This reaction force lifts the hull and helps you pop up on step. They also help keep spray out of your prop.