The YN622C-TX fits on the Sony MIS with no problem, I use that to trigger the other yongnuo flashes. As an added bonus, I mounted a cheap Vivitar FB-100 ($20 on sale) to extend 2 other cold shoes on the A7II, mounted a pocketwizard plusX on it, and ran the PC sync cable between the PlusX and the YN622C-TX. This basically lets my sekonic L-478DR talk to the PlusX, and the PlusX tells the Yongnuo to fire, and the yongnuo controls all the other Yongnuo receiver groups (in manual mode).
It's pretty slick! Take it easy :)