Nope, you can’t!
The logic is precisely inverse to what you say! If you use the S2 reflector/pill in a S2+ (which is already shorter than the S2) you will eventually reduce the space you already have for the 18650 battery with and 18650 tube.
The mod you can do to have that configuration is to turn the S2+ into a triple, by using the S2 pill in a S2+ .
I’ve done that mod inspired in some other people’s mod, too.
You have mine here, and you have this thread of g_damian, and this CRX thread, and this Firelight2 thread, and even some comfychair .
See those and you’ll be able to fit an 18650 into an S2+ with an 18500 tube 