Acceptable technical kit

Amendment 1 : My one and half litre suit inflate fits within the frame and gives me more options in event of complete dil loss.

Yep, clipped off just like a stage. Only difference is I would pressurise a stage and turn off, then turn on before using. Bailout is always on as I may need it PDQ.
And my drysuit inflate can be another option if I run out of diluent, it's always got air in it and is marked "breathing Air".

SmartMonkey

Mix a few % of O2 in it?

Joking joking, I know narcosis is proportional to molecular weight and Argon is 40 to nitrogen's 28

Harry

How would you breath it?

Ah Argox territory James your presence is needed in this thread

I still want to give that a go - get narked off your moobs all in the relative safety of Capernwray

Plug the inflator hose into a manual add valve and press inject?

I'd quite like rum and coke in mine.