I have had success using standard tissue paper from craft stores.
I buy white, so it can be dyed later.
What I did was cut a square large than what your covering, lay it on top of the load, spray it with wet water (water with a tiny bit of dish soap)..
work it into the shape over the load, the way you want it... Don't worry if its not purfectly smooth, and fold free, on the prototype, they don't get the real tarps perfect either...
Once its positioned as I like it, trim excess with an exacto, then take an eye dropper with some diluted white glue, and soak the tissue paper down.
After a day, it should be dry, but it will still be a bit fragile.. Then I stain it any color of canvas you want. (usually Olive or Khaki,) and stain the tarp. May take a couple times to get it a thick color. I usually use very thinned down acrylics, and a paint brush. I thin it almost like water.
Once the tarp color is right, then I go back and add decals if necessary. (some tarps have letters, numbers, or names spray painted on them). Decals should look like they were stencils. Usually white or black paints were used on the prototypes.
Once decalling is done, (if it was neccessary) then I go back and do washes of brown, earth, and black, (again, as little or as much, the more you do, the older, and dirtier the tarp).
I finish up with a fine tip sharpie marker, drawing bungie-cord ties, though with some thin nylon thread, rope could be simulated.
Once it all dries hard, the canvas with look pretty convincing, (I think so) and with all the washes, paints, and the diluted white glue, it seems to hold up to normal handling. (which means don't do trying to poke your finger through the tissue paper purposely)... LOL..
Try it out and let us know how it worked for you...
