I guess it would depend entirely on the costume.
Suggesting and "alternative" makes me think that they aren't an important design element - so I'm wondering why they're needed at all - without knowing that, can't come up with any alternatives.
Or is this completely hypothetical ?
Being busty shouldn't stop someone from wearing suspenders either over or to the side of the breasts. If someone was having a problem they should either take pictures or describe in-depth what the problem actually is.
Disclaimer : This post written by a Grumpy Old Man
Actually in the pipes:
- Remaking Ser Loras doublet.
- Luke Skywalker, A New Hope
- Wind Waker starter costume in swim material
Eventually: Paul from Dune, Faramir, Harry Sullivan