In the manual the skirt is simply bent into place and fastened to the transom skirt support blocks with temporary screws.
There is no recommendation on how to achieve this without eight hands or several helpers, and a large dose of luck.
One try at bending it 'freestyle' confirmed my suspicions, and I moved straight on to my contingency plan of fitting temporary support blocks to hold the skirt in place when fitting it.
I fitted three wedges (port, centre, starboard) with bevelled tops to match the slope of the transom skirt.
A test fit went without any difficulties. Here is a view from inside the boat.
The edge-to-edge fit with the top of the transom is not perfect, but is certainly adequate for a strong filleted joint.
Here is the port support wedge, with a sliver of daylight visible through the joint.
One advantage of having the upper stringer temporarily held in place is that it can be tuned before final fixing.
Here I have shimmed it to get its alignment with the sheerclamp as good as it can be.
Here is the test-fitted skirt viewed from astern.
I was pretty pleased with this result, but closer inspection the following day showed that the fit could be made just a little better, so I removed the skirt and refitted it.
You probably can't tell the difference in this photo, but this is the improved fit seen from inside the boat.
As mentioned, I was able to get a good fit for the upper stringer by tuning it a little, as this view of a level across the port seatback shows.
The bubble is smack in the middle - result!