At this point I've probably rebuilt the framing 5-7 times trying to get the boat straight. It goes in fine any way you want to put it in, but I'm finding if it's not done just so...the bottom won't align, and then you can't make it align unless you redo the framing. I've also rebuilt the dagger trunk because I think I misinterpreted the plans. there was a place where it looks like the rear insert ends above the bottom of the trunk and as I was assembling it seemed like that would be impossible to seal.
If you look at some of the pictures you can see the old vs new. I also extended it 12mm so the whole trunk could go through the bottom of the boat.
The big problem with getting it aligned came from the dagger trunk. Since it's just one piece it is much easier to misalign. So I ended up cutting a piece of strapping to the same length and using that to help square it. That and a speed square.
There was also a time when I noticed the seat sides had pulled away from the transom. The top (or bottom) was still touching, but the rest had pulled away by at least 3-4" so that threw everything off...
I hope it's all set now. My diagonal measurements are exactly the same