|Hi Michelle. We are no experts on sewing, so we can't say much about how much cloth should be doubled up for hemming, shrinkage factors, or how the seams will look.
We also don't know if there is a preference to horizontal or vertical strips.
For example, you could have 3 horizontal strips of length 34 feet. You'd "waste" not quite 20% this way, but it would probably be visually the best seaming. This would require 3 34 = 102 linear feet of fabric. You could also have 2 strips of length 34 feet and one of length 17 feet. Split the short strip lengthwise to get 2 strips of width 2.5 feet and length 17 feet. Join them to get a strip of width 2.5 feet and length 34 feet to cover the stage. This takes 85 linear feet of fabric but you may need to add a little for seams.
If you want vertical strips then, for example, 7 vertical strips of length 12 feet and width 5 feet would cover the area with 7 12 = 84 linear feet of fabric and only leave you a foot of material for 6 seams.
Speaking theoretically you need to cover 34 x 12 = 412 square feet. At 5 foot width in the roll, that means an absolute minimum of 412/5 = 82.4 linear feet - less than a third of a whole roll of fabric.
Lots of other options (designs) would be possibly, but these are the simplest and least labour-intensive.
Stephen and Penny