If I can get a flat first layer out of a Modix Big Meter with 21x21 you should be able to get one with the 180x.
Bed assembly is critical to start as flat as possible and minimize warping.
And a thicker fatter first layer can go a long way.
The trick to probe only he printed area can make a big difference as well.
I don't know if or when an increase to the limit would be coming. If it did, it would probably only make it to Duet 3 boards due to the memory limitations.