Take a look at Para-Wings. They are available from a number of manufactures/retailers in a variety of sizes. Perhaps not "Camp Sized", they are certainty big enough to cover a small tent as per your picture.
The biggest challenge though with pole supported tarp systems (of any type) is the anchors. If you don't have trees, you will need to use the ground. Traditional stakes are not very good when there is wind loading on the tarp. You could build dead men, but unless you have a convenient logs to bury, they might not be so good either. Consider building rock anchors (essentially, bags filled with rocks)
Hope this helps.
