I'm about to start on a new kayak, and the designer uses an external strongback. I've done internal - so looking for direction rather than re-inventing the wheel. This boat measures 18 feet - and as such, the strongback, as well. 1" X 6" planks, separated in the middle are recommended - that's a long couple of boards to haul home on my minivan! How do most do this - scarf a couple of shorter planks?

Thanks.