Serious question:
Does anyone have, or have practical experience in using, one of the portable oxygen concentrators, such as the Innogen G3? There was a writeup in KitPlanes about them several years ago and how having a limitless supply of oxygen changes your view of onboad O2 such that you're now more likely to actually use it when you otherwise wouldn't, like above 10,000 but for 'only' 20 minutes, or above 5,000 at night.
From what I can see looking at CAO108.26 portable O2 systems can be used so long as they can meet the mass flow requirements specified in that order, but unless you're flying high solo regularly, it would be a fairly expensive exercise to fit a 4-seater with these things...