Well, it's done & hanging in my backyard. I got a 12 x 12 SG camo tarp from redbeard & changed it "a bit". It was: 12' X 12' square with a corner to corner ridgeline of 16'
It now is:
A 13' ridgeline, 5'4" from ridge to bottom edge, 3' 10" bottom edge. And, grossgrain ribbon around edge also forming 6 tieouts: The ribbon goes from middle of one bottom edge, to a corner, forms a tieout (reinforced) then continues to the next corner, etc. Hancock fabrics was out of my first color of grosse grain ribbon, so I have 1/2 in medium green & the other in a sort of tan color, which actually looks better than one color. I also removed the 5 tie outs that are on the body & seam sealed the ridgeline. Since I use it 2 to 5 times a week, I am going to put re-coat waterproofing on the outside of the tarp. This decision is based on the fact that the 9x9 seemed to loose it's waterproofing rather quickly under the constant use I put it to. Yea, it adds weight, but if it keeps me dry, it's worth it.
I got home from work about 3 PM today & set up. WOW, lots more coverage than the modified 9by, (bottom corners cut off) with about the same weight as the unmodified 9by. Just guessing on the weight thing, don't have a scale, sigh.
Turns out I can't measure, so the ridgeline is about 4" longer than on the 9by, but I'm OK with that.
Sorry, no pics. Still don't have a sutable camera.