Current/voltage at LED and current at tail would be interesting to know.
If using a brass button on the driver like schizobovine you will want to thin the ring otherwise your batteries will be way too loose. S2+ host has a lot of extra room in it as it is.
I think the 18350 tube is a bit tighter fit though if I recall. Age old S2+ problems I suppose.
User kiriba-ru sells a really nice copper single pill with a custom thin ring (pictured bottom right) that I highly recommend for this type of build:
