best practices > syncing video playback multiple computers > long distances

Hello All!
I have been looking thru the forum and found a few use cases, like below,
https://cycling74.com/forums/syncing-video-playback-with-udbsendrecieve
and have been checking out the Brightsign players too. - cool gadgets out there.

BUT - mainly I would like to hear some real world experience/feedback/thoughts/suggestions.

BACKGROUND - i am speccing several projection mapping gigs this winter all involving the same big hurdles.
3-4 projectors with a computer each for playback - all with monster throw distances - All projectors in different buildings around a square (think North South East West sides) - No way to run a hardwire ethernet cable to sync them. Each gig is 15 minute pre-produced segments twice an hour every night for a week.

My current theory is to dust off my old sync patch I built a while back that uses udp pings (it worked semi-acceptable) or maybe leverage Ableton Link into the patch. Crazy-accurate playback is not deathly important, but if I can keep it to 2-5 frames the client can deal with it.

Then - find a big-azz-industrial-power wifi router to sync everybody up. The potential wifi congestion at each gig is unknown, and my single biggest fear... Local commercial internet is available at all projector locations, but I see that as a seriously un-syncable can of worms that i have no interest in eating.

What are your thoughts, oh Much Wiser Maxxers?
thanks very much for your input.
jd