Very nice setup. Well done. I have thought about getting some of those SOTABeams units myself.
For my (ultra)lightweight setups I have been using 100-150 pound kevlar kite string for the cords. They weigh basically nothing, are very thin, they don’t stretch at all, but are very strong. The only challenge with them is when the antenna is set up, they are so small, they can be hard to see.