Your idea is similar to what has been suggested here
I really like that idea. It is the only way to reduce Q times and enable people to play the game mode they want without hosted games. However ElementUser said this is not possible.
I am no expert in programming, but I think it is not something that would need that much work to get implemented.
I would definitely donate a huge sum for making this happen ?
What are the conditions to get Grimm's Crossing back to Matchmaking ?
Either way 2v2, 3v3 or 5v5 Blitz Mode. Or all Options available and you can choose which one you like on this map.
Really, public games isn't a cool alternative...