I know about the mod on BloomBase that makes breast sliders unisex, and while yes I have used those to reduce the breasts a female mesh gives a male sim, I'd like to know how others in the past have made drag without breasts. I've looked for tutorials for a while now, but haven't come up with anything that explains the ancient art of male boobage removal.
Thanks in advance to anyone willing to help me with this!

You should be able to just open up the mesh in Milkshape and squish the boobs flat. There will still be boob shadows on the texture - they're easy to get rid of. There will be some texture distortion where the boobs were... that's harder to get rid of, but shouldn't be too visible in solid colours.