If I were you, I'd get a hold of Brandon first.
When I biffed my tarp a couple years ago, I emailed Brandon. He recommended using a scrap piece of material for a patch and use GE Silicone II silicone caulk for the adhesive.
At the 3:00 minute mark of this video you will see my two patches on my old BMJ tarp.
Here's a thread on my fix for my down booties that ended up with a hole in them. I used the same method as the tarp.