Cool just tested a few more combinations. You can roll the silicone on the paper just one layer and it works pretty good, but it must be tough paper as its very sticky (i used one of the newer rollers, the foam ones, not the mop ones). The xylol helps to thin out the mixture for easier rolling, then evaporates pretty much completely when its dry, leaving just the silicone, so this is a better approach.
I think if you use enough xylol ( 2:1 ratio maybe ) you might not even have to roll it, just pour it on, as long as theres something there stopping the flow ( couple layers of tape, wood, exc )
The result of one layer of pure silicone or two layers 1:1 xylol/silicone is about the same, good points, tapping, or dragging.
I do NOT however have the drafting vellum required. Will try tracing paper, also do not have projector, so dunno what these things look like with picture on them, sorry =(