Thanks for the input. We thought of switching to a canvas, but were worried about the additional weight. Did your canvas add alot of weight to the shanty???
Also, we currenty have 2 tarps doubled up. We have a thicker, gray tarp on the inside, with a lighter blue tarp on the outside. Its not super bright inside, but its definately bright enought that we dont need a light to see what were doing. As you know, its good to be as dark as possible when you need it.
We have have neglegted to add additional tarps simply because connecting them to the wooden framing becomes difficult, and the connections become weaker.