[2020] I saw a 1x3 cell ship roll up on me today. Will the player be able to build in that way in the future? (Currently limited to 2x2)

It's available! The "+" button up top left next to the ship selection button creates new ships. Different types of canvases can be chosen there.

You can also swap out the default one at the mining station start using the same method and build a 1x3 instead.