Agreed, bmi (or really weight, as I'm not changing height) isn't everything, but it's measurable. I was 7.3% bf by dexa at 71.5kg. No idea what my % will be at 68kg, but I do know that climbing feels easier.
At bmi <19.5, I don't have a spare tyre. I have ripples. At Bmi 18.5, laying in the bath isn't comfy. Somewhere between the two is my target for lel. I'm definitely a "hard gainer", so what's a reasonable target for me wouldn't be for others. I've got muffin tops at bmi 21, whereas others wouldn't.