More graphics tiles

[someone]

...is it possible to put the Microbee into a 32 column mode? That way, the number of tiles available are effectively doubled (since the screen can be filled with less).

This is what someone often does. Have a look at the doppelganger posts on this forum for some examples.
It's very important to use 40 column mode for a 32 column display otherwise the keyboard scanning on the alpha and alpha plus models will be incomplete.