Download: Easier Mini Beam
This mod increases the Mini Beam length by 2 pixels, from 45 to 47 pixels.
This makes lining up 4-room swipes much less fiddly, without allowing you to hit any additional rooms or tiles.
This only changes the Mini Beam on Stealth A and C. It doesn't change enemy Mini Beams, as that might let them hit additional rooms with some of their swipes.
Note for purists / win streakers
Because this makes four-room Mini Beam swipes much easier, it would not be acceptable for no-pause win streaking.
For pause play, it really shouldn't matter, as you have all the time in the world to line up your swipes.
Technically I suppose it changes the timing of bio-swipes and Zoltan Shield piercing, but to such a minute extent that I can't see it making any difference.
This is a new mod, however, so I don't yet know whether it will find widespread acceptance for win streaking with pause.