[mturmon]

OK, but that's not addressing the problem raised in the OP.

Dedicated CubeSats have largely filled the smallsat niche. I would expect the Starlink mass has been carefully optimized already.

There are interesting mission concepts (telescope + star shade; NEO detection [1]) that are in the works with dedicated CubeSat constellations, but yoking them to another spacecraft bus with its own constraints doesn't sound likely to succeed.

[1] https://www.aanda.org/articles/aa/full_html/2017/07/aa29809-...