Meetup Route Distancce

A question for the collective hive if I may.

I am hosting a series of races for my club using zwift. I am having to use the meetup function, which isn’t an issue, but when I select a route it gives me a distance, I understand there is a lead-in, but often the route finishes a long way after the usual route banner. Getting people used to the idea of keeping going until the blue fence is proving a challenge!

I use zwiftinsider as my source of information which is usually pretty thorough.
To give an example, creating a meetup of tempus fugit gives a distance of 18.2km but zwiftinsider says its 17.3 plus 2.4 lead-in.

My question…is there a way to reliably calculate the actual distance from meetup spawn location and the finish banner so I can shorten the gap between banner and fence? If that makes sense

Not really, and just to add to your woes, the distance is per person, not the race. So if 2 of you spawn 200m apart which quite often happens the one persons finish line is 200m in front of the others.

So a sprint finish might finish earlier for one rider than another.

I’ve experienced the opposite.
Was invited to a meetup on the ‘Big Foot Hills’ route, which is 42 miles long.
Throughout the ride, there is a blue and white chequered flag and a distance left to go.
Sure enough, as this approached zero, the blue finish gate appeared.
Passing the gate caused the ‘completed meetup’ message to appear and after a short spin down, I saved the ride.
Only afterwards, did it become apparent that, due to the lead in, I was a mile or so short of completing the route, and had been robbed of the route badge.

Surely, it’s not difficult for the length of the meetup to be set to the length of the route AND the lead-in?

Now I know about this, I’ll be ready for it, but it’s annoying that I had to find this out on a long route.