I finally built a 1 in 5 turnout to the loose-heeled template from Templot.
But as suggested by Martin Wynne, it is not loose-heeled.
So no complications with pivots.
This has resulted in the blades being a bit stiff.
However, I have tested with short-wheeled rolling stock and so far there are no problems.
It will be a while before I test under traction as I need to sort out actuation and wire everything up.
The real test comes with a tender loco.
But if it fails, it will be no worse than my previous efforts with an A4 (and an A5 come to that).