yes you should take a portable oxygen system. seems to me you end up buying the canulas...would you rather rent something stickin gin some one elses nose.?
any large FBO should have a system for rent. don't think things are cheap, just a refil may be in the 25 dollar area.
I can't tell you which FBO to try, call around. Which airport are you taking off from? check there first.
you might also do this. go to airnav.com
enter a bay area GA airport like KSQL or KPAO.
you get all the runway info, but at the bottom is a list of FBOs and services, so call em aske em arrange it but get it the day before you takeoff to take a look at it and learn how to use it.