Don't stick it permanently unless you always carry the gas bottle........ if something happens (even something minor) and you have the sticker and no bottle they'll take all of the compressed gas hazard precautions.
Anyway, just buy a couple of extra tanks for your marker, fill them at tourneys/site and you are sorted.......... seriously, you can get a few marker tanks for the price of a dive tank and how much gas will you need between tourneys?
That way you avoid all of the lugging about, expense and dubious legality of decanting from bottle to bottle.
(decanting just means transferring between bottles....... gas, liquid whatever).