Two prusiks, as I have offered is not in the realm of the unthinkable, nor are they so complicated that one can not inspect them easily.
No... but just COUNT the number of tucks and/or spins ! 
When you go over 2, you return to your drawing board - until all really easy-to-tie
AND simple topologically and/or geometrically knots are exhausted.
The testers should be exhausted before any of this is
done; and we shouldn't be so stupid as to just toss
out another & another-like-it-but-different knot tangle
on hopes that by some magic it might work (although
it brings nothing, structure-wise, new to the test bed).
And we do want to have a knot that doesn't require
copious amounts of rope!
Re-tucked
zeppelin? They've already done #1408
(roughly) and #1452, which slipped without hinting at some
promise
if only ... <slight revision>. To these, though,
what I wonder about is the variation in which such
interlocked-overhands knots made the U-turn a
turNip--i.e., turn 360 degrees and collar thus the opposing
S.Part. For there is some hint at least that the turNip
has some grip that can be enhanced by repetition.
(Recall that the in the Brion Toss videos one sees the
double bowline slipping, and a not-quite
mirrored bowlineholding to rupture.) I'd hoped that the cooperative
surround-&-nip-the-tails #14xx structures would get
sufficient nip esp. with the 2nd tuck; but maybe it's
the quick transfer of force that moves the 1st tuck
and thus quickly simultaneously is moving the 2nd
as well --no pause of stretching yield (and the movements
go in same direction, adjacent). !? <argh>
Roo has urged that
offset fig.10,
"stevedore" knot;
I wouldn't expect this to be at all strong enough for use
(breaking before some others slip?!), but the particular
nipping structure is something I'm trying to incorporate
into some other structure (such as the
blood knot)
--and keep running into the makes-bulky/awkward problem.
--i.e., a sharp U-turn that nips the tail(s) enough to give
resistance that then enables the rest of the knot to
be tightened further.
HMPE is so slick but also so
static that force gets
transferred/conveyed throughout the knot such that
it is frustrating the binding. Contrast this with tying
the highly elastic physical-therapy tubing, where one
would need to deliberately haul hard on parts, and
possibly try to lubricate the material, even, so as
to deliver some setting force, tightening into the
full knot!
Then, again, I wonder if even should it suffice to hold,
would the
blood knot with tails knotted jointly into
an
overhand stopper prove to give too much movement
on in-practice loading on further tightening such that
heat then dealt a lethal blow? But this is not a trim knot;
just maybe one that can do the work, in a pinch.
(NB: the
blood knot can be tied so that the tails
exit together, same direction (what I have in mind for
the stoppering of the tails), or in opposite directions
(which I've seen done even though it amounted to
an asymmetric knot --a half-turn difference between
halves-- in some commercial fishing joining of heavy
(3mm?) monofilament nylon line.
--dl*
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