I'd like to thank gmcttr and PuckerFactor for the extra kick in the pants and encouragement to make this DIY tarp complete. Please follow along.
My tarp as first "completed".
http://img850.imageshack.us/img850/4449/1001070yz.jpg
Now with extra tie outs, with doors.
http://img220.imageshack.us/img220/139/doortarp1.jpg
And the inside.
http://img717.imageshack.us/img717/7991/doortarp2.jpg