Yes, yes silnylon does stretch but not endlessly, at some point it stops....
This is what I do. I set up the Contrail with the pole an inch or so shorter than it should (can) be. Pull the guylines taut and proceed to wash my self, prepare dinner, whatever. If the humidity has risen or has started to rain I re-tighten the tent before I go to sleep. If it starts raining during the night , then I just increase the length of the pole and it's good night from me. If there is a chance of strong winds ,I use all of the 8 guyout points provided. Typically I have a walk around "camp" before I go in for the night and at the end of that I check the set up again.
Franco