Maybe something like thisHaving 1 single lobby for TG is definitely better but then we run into the same problem which we have right now, too many people in one lobby.
If We can have one single RM TG lobby given current infrasture then there is no doubt that this is least complicated and better solution.
1v1 rm
Tg RM (rated or <1500 ELO)
Tg RM (not rated or >150 0ELO)
1v1dm
Tg DM
Other