I am surprised you can’t buy whoopie sling guy lines. I am even more surprised that high-end tents don’t come with them as standard. They have to be the lightest and most elegant option. You will have to make your own. I would say that the 1.75mm ‘Zing It’ would be an ideal size for the novice to work with. They are an elegant solution, and an interesting hobby to wile away the idle hours of a night (when you aren’t camping/hiking). Here is an informational: ‘How to make a whoopie sling’: https://www.animatedknots.com/whoopiesling/index.php It is really quite straightforward. All you need is a largish needle.
PS: Learn all about (and buy) whoopee slings and adjustable ridgelines here: https://www.whoopieslings.com/
Some other information about dyneema cord: https://www.arrowhead-equipment.com/blog/the-dope-on-rope For DIY, cord available eg here: https://dutchwaregear.com/product/zing-it-or-lash-it/ or here: https://www.tiergear.com.au/shop/shelter-systems/guylines-ridgelines-and-hardware/mallee-wire-1-75mm-dyneema-cord-per-metre
PS: Dyneema braid comes in even thinner styles, so that You could probably choose something like a 1 mm braid for guy lines on an ultralight tarp and never have one fail.
Further: In answer to a reader’s question, ‘How do you use them with tents?‘ Answer: You use it as an adjustable guy line (instead of using a tensioner like this: http://www.theultralighthiker.com/the-perfect-guy-line-for-a-hiking-tenttarp/). You would loop the eye for example through the tie out, then bring the rest of the whoopie through the eye. The adjustable loop would be attached to your stake. You tighten he guy by pulling on the tail.
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