I built a couple of external strongbacks from 4 straight 10' long 2X8 fir planks scabbed with plywood in the middle. I used 2X2 across every 12" to build a ladder. I didn't cut the hull portion of the forms out and measured down from the DWL to keep the dimension true, and then as long as my strongback was straight I only had to line up the forms for side to side. I cut out the hull portion of the forms later when the hull was complete and hot glued the forms into the hull in the right locations ( I marked them with a pencil before removing the forms from the hull) After removing the hull from the forms I immediately glassed the inside so that the forms hot glued into the hull kept it from getting wacked out of shape. Made lining things up later a lot easier, and I like to get the tough jobs done ASAP, and glassing the inside of a hull for me is always a tough job.

Bryan K