Simple solution to the knot problem.

Tie your knot's and then use a zip tie to hold it in place - on the ropes past the knots.

You can buy inexpensive - small GB zip ties in Lowes - for a couple of dollars per 100 ties.

Tape will also come loose after prolonged exposure to sun and weather.

Then again, I limit most of my purchases of electrical tape to Scotch 33 brand 3M tape. The cheap stuff never seems to hold up anyways.