Need your opinion about attic ventilation.

I have a small Cape Cod home which I have removed the siding, tyveked it and installed all new construction aluminum clad windows.  I will be replacing the siding with cement board. The roof was recently done with ridge and soffit vents.  The Cape has two finished rooms upstairs with a small dormer over the half bath.  Since the upstairs bedrooms were extremely hot in the summer months.  (A New Hampshire located home), I installed a temperature and a humidly controlled automatic fan in the small dormer above the half bath.

The problem.  After installing the fan, I later found out that I created a problem because of the ridge vents.  I found out that you can not have two types of venting together, as they will “short circuit”.  ie, the fan will pull outside air through the ridge vent above the fan, as it is only a couple of feet away from the top of the fan.

My initial thoughts were , that I either have to remove the new fan, or remove the ridge vents.

My new thoughts are as follows, which I would like your opinion on.

The Cape has knee walls, and is insulated with fiberglass insulation from the soffit to the top of the knee wall.   (I added foam channels between the insulation and the roof deck).  I am thinking of continuing the foam channels up to the ridge vent.  This will give me a clear shot from the soffit to the ridge.  Add insulation all the way up to the ridge vent, then seal the attic with 1/4″ plywood, both above, and below where the knee wall meets the roof joists.  This will allow me to have ventilation from the soffit to the ridge with no leakage into the attic.  Keeping the roof deck cold in the winter months and allowing me to use the automatic gable fan in the half bath dormer, which will also  be sealed the same way as well.

What do you think.  Am I all wet or is this acceptable.

Thank You, Ray