I showed this to Plasmo earlier and he said I should post it here as well, so here I go.
Video linkage.
I worked out this technique 2 days ago and thought it was rather nice if you want to beat this boss without bombing and also avoiding his last bullet spam pattern which he shoots in a way that makes the blindspots hard to utilise (after the first spread).
So I thought, let's try how close I can get to this guy and found the blind spot at the top. You can neatly positition yourself with the help if the HIT counter number. your nose should be a bit above the bottom bar of the first number and just beside it. It can overlap a bit but not too much, there is only a little bit of room for error.
The hardest part is to get back up after the boss shots out the 8 little guys after the first spreads, since you have to get them all of your risk being shot in the ass.
With a bit of practise this is quite doable (esp considering I am not the best of players)
Also the video is not of a full run, but utilising save states in wolfmame 0.99 to practise bosses.