It's great to see you getting your kids into hanging and hiking. I tried to get my neice to go and she wants no part of it, I think it is the 14 year old in her coming out.
I use a wiretie instead of whipping. All it does is keep the gathering together. It holds my 220+ lbs self just fine. I had problems when I first starting whipping with getting it tight enough. The hem on the end should stop it from coming off.
Is that too much to ask? Girls with frikkin' lasers on their heads?
The hanger formly known as "hammock engineer".