Clouds on stage: Seeking advice from techs

Dry ice is the easiest, but to get the amount & deck coverage - I imagine you would require, it needs to be contained. Either by the use of ground rows &/or within a scrim & back drop {[cyc] [set piece]}.Dry ice hugs the deck & will finally dissipate over a period of time. You could pad it out with smoke,which will rise or refrigerated haze, which will rise as soon as it is heated with lighting.

Me I'd go with a ground rows of simulated clouds & belt in the dry ice from both sides.

These effects have a mind of there own, and are subject to any air movement. Of course low tech wafter's will help or deck turbo fans from the wings. The type you find in space gas heaters. Which I'm sure you could pick up from a Salvage yard.

Where are you doing the production John? especially if it has a Pit, as it will always find the lowest level. Also it's particularly good at getting into Drip Traps & leaving condensation. It doesn't work well with open GPO's, patch points or audio connectors.

However it will cost a few bob for the enough dry ice per show  possibly the machine hire, if you don't want to have the machines made up your self.