I really cant see what all the dufficulty is myself so long as you have
a: The top ring is keystone
b: The pin clearance cutouts the right way up
c: There is ONLY ONE expander ring to fit...in the bottom (parallel groove)
Possibly you will find it easier to fit the piston into the bore away from your bike??
Place wrist pin in the deep freexer for an hour or so
Place rags in the crankcase
Fit just one wrist pin clip into the piston
Fit the top of the piston / rings into the bottom of the bore
If you have a hot air gun or blow torch warm up the bottom of the piston (or even place whole lot in the oven for 15 mins)
Retrieve the pin from the freezer and quickly assemble to the con-rod
job done
It is a concern you said spreader rings (plural) Definitely only the one in the bottom, you will notice the bottom parallel ring is narrower...to accomodate the spreader ring behind it