As I understand it, the half flattened Sheepshank can be turned into a Span Loop having 4 loops. That's a monster!
And not at all what *I* had in mind --rather, use one end of
the
sheepshank for the twin eyes, w/o further modification.
Might a Midshipman's/AWNING hitch-like formation of a two-turn
half-hitch nipping by the S.Part suffice for security of this doubled
eye, sparing the (lower, for the paradigm use) half-hitch, enabling
the shake-free aspect? --i.e., make a 2nd turn, jamming this into
the first, for both stability & grip/nip?! (haven't tried this myself...)
I can't visualize this.
In that case it does!

It's simple : the bellringer's/sheepshank have a turn nipping
one end of a sort of hank of rope --typically one circle--;
make this turn as per awning knot, doubling it. Some sources
in fact show this variation for the
trucker's hitch, I think.
A sort of
cross cow hitch vice the simple turn of the
trucker's hitch is also more secure; it doesn't shake free
and is not so quickly formed (I might form the
c-cowand stuff the circles into it, adjust & set).
--dl*
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