No problems in relation to posting I'm glad I can help somebody out. I am a member of a few different U.S based fishing/boating forums and I find you're a great bunch over there, that I have encountered anyhow, I'm glad I can help out.
The 1670mm spacing is centre spacing on the mounting bolts, but like you said with minor differences in hulls it may change slightly. I got my basic spacing by having the yak upside down and seeing where the cradles fitted the hull shape best.
I did have a bit of trouble with the rear cradle in that there was a gap of about 30mm between the cradle and the 2 outer hulls with the centre portion of the yak hard down onto the cradle. What I did was cut my cross piece that the cradle was to be mounted to longer than needed. I drilled 1 of the bolts mounting holes and sat the bolt through the cradle into this hole. I then sat the yak on the cradle and pulled the center of the cradle down with a small clamp. This tended to spread the mounting points and allowed the yak to make contact with the cradle as you can see in the photo. I then marked the location and drilled that. I then needed to cut some small wedges as the flat mounting pads, where the bolts go through the cradle, were not flat against the timber. These wedges are between the cradle and the timber cross piece, if you zoom in on the rear photo of yak on trailer you can just make them out.
It was a bit of a fiddle but it was the only way it would work to get the yak to sit on the cradle, it did not matter where I located the cradle along the yak as you are governed by the distance from the keel to the inside edges of the 2 outer hulls.
To get the correct angle, I had the cradles fixed properly to the cross pieces. In the photo of the frame on its own you can just see the cross piece for the rear cradle is fixed by 2 fixings through the side rails into the cross piece. I just fixed both cradle/crosspieces originally with the top fixing and then sat the frame onto the trailer with the yak on top of the cradles in position and then manipulated the cradle/cross piece untill it fitted the yak and then fixed it off properly.
I guess you could separate the frame to store if you needed to. I had just taken the photo's as I was building the trailer up for just this purpose, as I had'nt seen anything online for the PA and cradles, so I thought I might be able to help someone out. I store the yak on the trailer as in the photo and it's great I'm really happy with it.
I bought the cradles from Austin Canoe and Kayak they were fantastic. I got the cradles delivered to my door in Australia for $331 in 6 days, they were going to hit me $480 for a set in Australia and then I had to pay freight
If you need anything else give me a shout, I'll check back tomorrow, I'm calling it a night.