I'm considering a sprit or balanced lug for my passagemaker with a polytarp sail. I would be fashioning a mast from a spruce 2x4 and footing it through the forward seat onto the deck below. No Shrouds. I was thinking that I would run the mast through a length of pvc thereby keeping the front compartment water tight, as well as rounding the mast to allow it to rotate. Any thoughts?