I did the same as animal control with the bowline -larkshead, fed the eye of the loop thru my webbing loops on the tarp, then pulled the entire length thru the eye, with another bowline loop at the end. With six feet of cord on each tie out. I can use it at six feet, or slide both loops together for three feet, as terrain/trees dictates. If needed I can do the marlin spike on the stakes as well. Simple.
For tangles, I found a few minutes of time spent during takedown saves trying to untangle the birds nest later. My next tarp will have little hairties (elastic circles) sewn to the webbing tie-outs. Presently I make a nice wrap around my fingers and tuck it in the webbing loops. Then roll up the tarp.
I figured if the line is so strong that my tarp breaks (that would not be good)or webbing and stitches are ripping out, I would make the line the weak link. I carry a little extra cord with me anyways, I can just tie on some more. Mason line is cheap, defintely not heavy, and bright for clumsy people.
On the ridgeline I use paracord, in a different color than my outside tie-outs, makes set-up less confusing. I haven't noticed any excessive stretching, again it gives some, which I think is a good thing. My tarp stays tight on a weekend hang, without having to re-tie. String is cheap. Tarp is expensive.