I'm thinking about a JRB Cat tarp or WB Superfly though both are 11' long and I've read that may or may not be enough for a hammock as long as this.
I'm also thinking of just getting a Claytor diamond for now and wait until something more suited specifically to the Switchback comes along. It's 13' long.
In any case I want an inconspicuous color. I understand from Scott Littlefield that it's hard to find silnylon in more subdued colors except for grey and black which don't seem quite stealth enough.
I'm also very interested to try a winter/door type tarp. Using the HH diamond I sometimes have to pass up nicely hidden spots to find one that has more natural wind protection which can be hard to do from the road on a bicycle.
I have no illusions that more stealthy colors will make me invisible. At some point the tarp outline is going to be visible to anybody who's looking at it but if you don't notice it first then you're not going to look at it. Somebody might pass by close enough to notice it but there's always a good chance that they're paying more attention to where they're walking or driving and if they don't catch the color of your gear out of the corner of their eye then they won't notice you.
I don't expect not to be noticed ever, just to minimize it as much as possible while still enjoying a comfortable and convenient hang.