I don't suppose you have any experience in hosting convoys and/or being part of the event CC team.
In every convoy I attended, either by TruckersMP or by VTC's, the convoy lead has always followed the speedlimit. In fact, the convoy lead is usually driving way lower than the speedlimit when the convoy departs to ensure the gaps are minimal. A convoy of 120+ people takes a while to leave the city. After everybody has finally left the city the convoy lead will usually speed up to about 60 or 80 KPH. I have never in my life seen a convoy lead driving anything higher than 90 KPH.
If you are near the front of the convoy then your problem does not even exist.
Because of the amount of people involved in a convoy, gaps are inevitable. People driving 150 is purely because gaps are created and they want to fill the gaps. Forcing everybody to a limit of 90 KPH would add time to the convoy. And I am talking about hours of time. Not to mention that it isn't really a convoy anymore at that point. Just small groups of people spread far apart from each other.
Making the convoy shorter just decreases the quality. If you are in front then it will be over in 30 minutes. If you are near the tail then it will take a bit longer, but you are still only seperated in your own group of people and not part of a convoy.
EDIT: (not related to what I wrote above)
Also what is this all this talk about Sim1 changing to 150? Or bringing EU2 back?
Just because 1 out of the 3 surveys mentions server configuration?
That could mean enabling/disabling cars, save-edits, the application of NCZ areas... It doesn't mean that for a fact TruckersMP wants to turn this into a racing sim...