How far apart are the posts?
I'd think that this is a quite simple task (putting up
the string), and one would just wrap the string one
turn around each successive post, with tension;
the intial post can be tied off with perhaps two
full turns and a clove hitch of tail to line (aka
"two half-hitches"). Possibly, the entire task can
be done in several sections (so, string only so long).
--dl*
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