I host a lobby almost daily that tries to recreate the Tokyo rain event.
The most difficult thing is to get the drying part right. It's usually much faster to dry out but can also be longer, so it's quite random in the end.
I just use the first weather spot for rain R02 and have gradually better weather up to the end.
I also host a double tempo race on 6 laps and 50x tires 6x fuel, it seems that this double tempo lobby is easier to fill up.
I also forbid the use of swapped engines because the race engine swaps break the purpose of this race.
Feel free to add me on PSN if you'd like to join. Your account settings forbid friend requests and messages.