I have tanks of both nitrogen and carbon dioxide (CO2), but since
CO2 is much cheaper I use it if there is not a specific need for
nitrogen such as in preserving food.  I have never tried it but
I bet you could get by with minimal equipment using dry ice which
is available everywhere now.  No need to buy a tank and regulator.

The same flame test will let you know when the tent is filled and
only need to have an exhaust at the top if you put the dry ice
on the bottom of the tent.

Best regards,
Spencer Chase
Garberville, Calif.
http://www.spencerserolls.com/