you can set your tile grid to 32x32 in MV (though I don't know if this affects the editor, never really messed with that).
I'm using 32x grid in my MV project, so I can chime in on that. You pretty much need two sets of tilesets (and parallaxes) set in '\parallaxes', '\parallaxes_small', '\tilesets', '\tilesets_small' folders. Regular Tilesets/Parallaxes folder has them with 48x48 grid (that you use while mapping), but then the game uses stuff from '\..._small' folders.

