Not sure of your construction details, but if bulkheads aren't in place yet, you may find it easier to work from the cockpit with tools on long sticks. A small headlamp is a great help and can be had for not too much cash from most outdoor places - even Walmart has them.

Different boat so I'm not sure how well the method would translate, but the Pygmy method fillets most of the seam with a syringe on a stick, and tape only as far as you can reasonably reach. Outside, the deck glass is run over the deck and down the hull an inch. Kind of like deck glass and shear seam tape in one step.