Have the same problem with a Hugyfot housing and D500...
Sometimes the trigger is ok, sometime not. Testet Aquatica and Turtle.
So i had the same idea:
Triggering one YS 250 pro, from there the next,....
I have longer cables, but still too short.
So i have used a piece of plastik, with a hole that fits tight enought for the plugs, and put the kables in from both sides.
Works fine, if the trigger does...
Today i will try to pimp omne of the cables.
If it works, will be documented ;-))