I’ll just comment regarding the SJR proposal.
Your updated diagram looks more realistic to me – with SJR it would be normal for the mast to be just a little forward of where a Bermudan cutter mast would go. However, when it comes to the actual numbers, a scale drawing will be better – it is a bit dodgy trying to guess the CLR position off a photograph – even an exactly side-on photograph is not exactly a profile drawing.
If you don’t have any scale drawings, there is another approach you might take, regarding a single-mast SJR. It has been found that the centre of effort of a SJR will be pretty close if it is placed to match the centre of effort of the original Bermudan rig. (This may not necessarily work for other junk plan forms, but it does seem to work for SJR).
Since you have the old rig, and you know the old mast position, it should be possible for you to calculate exactly the position of the centre of effort of the old Bermudan rig.
Now the centre of effort of a Amiina-type SJR is near enough on a vertical line through the midpoints of the lower battens. You can now move your sail plan until the SJR centre of effort coincides with the original Bermudan centre of effort. That puts the SJR sail about where it should be.
The mast centre-line of a Amiina-type SJR runs through the points on the lower battens which are 1/3 of the batten length. That defines where the mast position will be. Usually that works out just a little forward of the original Bermudan mast position and I think it will in your case too. (Though in the case of a Bermudan sloop with a relatively small fore-triangle, which is unusual these days, the mast positions might even coincide).
So that’s a method you could use to get a SJR to have about the same helm balance as the original Bermudan rig, without the need to try and guess the CLR position.
Just for an example, I took the original drawing of Amiina’s sail (as designed by Slieve) and scaled it to 55 square metres. I think most people will say this is getting pretty big for a single sail. The scale factor for area, to achieve that, is 3.41. The lineal scale factor is the square root of that (1.85) and if we apply that to Amiina’s mast, it comes to 13.6m above the partners. Amiina’s mast is actually a little higher than it needs to be (though that is an advantage) – which means you might be able to reduce the mast height a little – maybe just over 13m – above partners – but it must be at least as high as the peak of the yard, or otherwise you will have other problems.
I think these calculations will fairly closely match the single-mast SJR that you have proposed – it will be a starting point, anyway. It does look to me like a rather large sail on a rather tall mast, but those are matters you will have to evaluate for yourself. By increasing the number of panels, you have made jibs which have an aspect ratio of less than 1 (ie they are wider than they are tall) so you are in new territory with your sail design. Also I am wondering why you would divide the top panel into two parts. Sail design is evolving, of course, and there may be some ideas that you are keen to try. I think you might enjoy a discussion with Slieve, who would be the best person to advise you on designing this type of sail.
I took the profile photograph of your boat, and from its length (32’ = 9.6m) I established a scale, and just took a guess at where the Amiina sail plan looked about right (just "eyeballed"). By following the procedure outlined above and establishing the original centre of effort, you will be able to get it closer to correct. It does look like a pretty lofty rig to me.
I wonder if 55 sqm really is a suitable sail area for this boat, it does seem rather a lot.
sketch modifird 12/12/2021
correction 14/12/2021 should be 6.01m battens