I like the paper idea (butcher paper, which has a gas barrier, was what I was thinking) and that was what I wanted to use in the first place. I had planned on impregnating the paper with various salts that would give different colors to the burn. However, butcher paper is heavy, and then add the weight of the glue to make it air tight, plus the weight of the salts, made me worry how much hydrogen I have to enclose to lift it. If I could find a gas tight, light weight, cheap paper (hard to beat the price of bubbles), I would take a second look at the paper idea. Also if I’m going to make it large enough for people all over the playa to enjoy looking at that’s a lot of paper to handle with the way the wind comes up so fast there. Those are factors that pushed me into thinking about using foam. The more I research this the more I don't think there is anything that would stiffen the foam that wouldn't weigh too much for the foam to lift. So now I'm thinking that I could use something like surveyors tape (something very lightweight) that can be unwound in the foam that will burn and carry the flame the entire length of the foam snake (I’m afraid the wind will break up my foam into several sections and then the flame will not go the entire length. This needs to be able to burn if wetted by the soapy foam.
Does that give you any ideas?….P.S. thanks for responding to my call for help!