5000 meter height gain

How do most pilots go about the 5000 meter height gain in the Sierras?
Somehow getting in a glider on a cold/windy Minden winter day does
not sound like me. During the summer I stumbled across a wave
condition behind Mt Rose but I was not sure about how the O2 system
worked and where/whether the wave window was open so I stopped short
of 18k If I was ready this would have been a perfect opportunity.
Seems difficult to know when these conditions will exist.

Another question is if you use the M&H O2 and you are staying below
24k do you use the cannula or the face mask? I think I know the legal
answer but it seems that the cannula is actually the preferred option.

Any advice would be appreciated.