Check out sod/landscape staples if you haven't already for keeping the irrigation lines in place. Six inches long, I like the ones with flat tops the best. 25$ for 500, cheaper for more.
Once you get it laid out with staples and the poly has been in the sun, you can go back and remove about half the staples if you need them elsewhere.
Once you get it laid out with staples and the poly has been in the sun, you can go back and remove about half the staples if you need them elsewhere.