I was playing around with some cordage last night and I started thinking about replacing the standard prussik knot used in the 'over the tarp' ridge line system with a constricting section, ala UCR/'Whoopie Sling.
I forgot to take pictures but I threw together a quick drawing to better illustrate this idea. For my experiments I am using Speer's No Tangle Guy L for the ridge line and some of the Dynaglide from opie's recent group buy for the constrictor section.
The constrictor section has a loop on one side, a 4-5" constrictor section on the rope, and a pull tab on the other end. The loop is used to attach the constricting section to the tarp via a biner or some other type of clip. You can give the pull tab a tug and it will allow you to tighten and adjust the tarp.
I just had time to make a really quick prototype last night, but I didn't have a lot of time to play around with it. I'm pretty sure it going to work. I'll post details and actual photos as my experiments progresses.