You'll need 2 pegs for each side for the tarp, unless you can find handy trees, rocks, etc. So you'll need to take 6 pegs all together - 4 for the tarp and 2 for your WBBB.
I've found the tarp pitches best when the two guys on the same side are angled away from each other a bit. My lines are just over a meter long (about 4' if you prefer) which is a bit on the long side but it gives me enough length to go to porch mode with my hiking poles if I want. I know I could have shorter guys on one side and longer on the porch side, but that'd require me to set the tarp up the right way round every time.
I usually carry an extra 4 or 5 meters of cord with me for multiple purposes (e.g replacement bootlaces) which I've one or twice needed as an extension to one or other of the guys when setting up on a sloping site.
The skilful traveller leaves no traces of his wheels or footsteps