Ok, but its gonna hurt badly... group 2 will probably demolish the competition, being able to start on RM, then have a full 60 minutes on RS, and just do 2 stops (group 1 will also have to do 2 stops).
Group 1 willl be on worn RH tyres and group 2 will be on fresh RS, for a full 20 minutes, thats roughly 10 laps, and laptime difference will be about 5-6 seconds. (3 seconds compound difference, and after 30 min on them, they will have worn down by another 2-3 seconds)
So if we asume that group 1 will have the same pace on RH as group 2 have on RM, wich usually tends to be the case, then we will have a 1 minute gap after the first half of the race, if group 1 then are 1 sec faster per lap, wich is the difference between RH and RM, and will have a bit better tyres and fuel, lets say we will be 1.5 seconds faster per lap, that will be just 33 seconds advantage, and group 2 will win with roughly 30 seconds.
I'm not saying change it now, I think its worth a try, but if it works out to be too much, can we leave it open to a change?