Why not just build the whole thing outside?

It would probably take less time than cutting it in half and reassembling.

You could cover your assembly area with plastic tarps to keep off rain between building sessions.

This would keep the sawdust, sanding dust and epoxy fumes out of the house, too.

If you start cutting and assembling the parts on a holiday weekend you could end up with something resembling a boat. Of course that means you woud need to scarf the panels a few days, or the weekend, before. (Things go faster when you have a helper. Maybe you can catch one by filling a cooler with beverages and using that for bait.)

Just a thought

PGJ