i imagine there would be lots of complaints if you had to be docked to MC
This is actually my preferred option for multicrew formation.
The compromise position should be that the potential guest Commanders must first dock at a Station, which then allows them to instantly multicrew with other Commanders who have an active Open Crew Slot within an arbitrary distance radius, something like 50-100LYs, which will preserve a sense of scale and geography in the setting.
Docked Guest Commanders would then have a "fade-to-black", and would then appear PHYSICALLY ON BOARD the host ship (no holograms needed!).
This fade-to-black would be the bit where we all suspend our disbelief, not much different from getting picked up from an escape pod "off-screen", or physically getting into the SRV "off-screen" like we already accept.
Alternatively, if two Commanders decide they want to Crew up but are too far away from a Station, then they can Crew up by instancing together in open space, at which point the Guests again fade-to-black to arrive PHYSICALLY on the host ship, and then their own ship is simply "Dismissed" away, just like we do on Planets when we're driving the SRV.
This uses current established lore, minimises our suspension of disbelief to levels similar levels to what we're already used to with death / rebuy.
There would be no need to invoke ill-thought out & setting-breaking disruptive technology, and it would give the feature sensible limits that don't undermine it's effectiveness, whilst maintaining all the other design features that get broken by insta-teleporting across unlimited distance.