Spreader tip modification for synthetic

[benz]

Are you thinking about having two runs of Dux begin at the chainplate, one of which bends inboard at the first spreader and the other which carries on past the second spreader to the cap? Because in that case you could do it--just lash very firmly with fine twine. you could even run a thin piece of Dyneema from spreader tip to shroud tang to prevent the spreader tip from sliding down.
But you can't have the same setup as now, with one lower wire and two that carry on from the first spreader with Dux unless you terminated at the spreader. The force on that leg that goes from spreader end up to under the second spreader would overcome any lashing and pull the spreader up.
I would splice the Dux around a Colligo thimble so that it stuck just past the spreader, then splice the two diverging legs to the thimble. Not very low-profile, but without having a custom-designed fitting specially machined for you, this might the only option.