I decided to use the weedeater line for a few reasons. One, it was on hand and like you said, it takes forever to get anything up here especially on short notice. I built those arrows about two weeks before we left. The year prior, I shot a two blade, fixed head and blew right through a musk ox and when they are in groups that could be dangerous in that another bull could be struck by the arrow. So the second time I went, I wanted to use a mechanical to avoid a pass thru, which required me to get a much heavier arrow for initial penetration. The arrow you see in the article was a small diameter Gold Tip Kinetic, and only allowed me to put 3 strands of line in them. So I switched to a Gold Tip Pro Hunter, which allowed me to get 5 strands in and that arrow ended up weighing closer to 650 grains. The key to using weedeater line is to be sure you pack the line in there tight so that it doesn't move around in flight.
I am sure there are better ways to add weight, this is just what I did.
Anyhow, I shot the arrows a lot, out to 60 yards, with no issues. My bull was at about 25 yards and the mechanical led arrow got about 24" of penetration, the bull went 60 yards and fell over. 63lb Hoyt Nitrum 34.