There you have it - a simple, cheap, and excellent sail that uses almost all of your 7x10 tarp and looks freaking great. I love the Chinese Lug as it really grabs people's attention and it works very, very well.

There are much more complex ways to rig a Chinese Lug (like having sheetlets pair the battens together, then a block for each sheetlet all running down to blocks on a boomkin and a single mainsheet to control it all.) These methods will help control twist, but I am not convinced they are required for a sail this small.