I'm not sure why it would ring truer... missing your chance is missing your chance. She would have those same feelings whether she's 5 years too late or 20 years. And the resentment and regret would be bottling up the later it goes.
Also I think the true age is a valid point and I'd love to see a production that doesn't make Rose seem 50+ the entire show. BUT it's never really be done that way in a major production. Maybe 40+. And today's audiences may not understand that people did everything younger and a 30 year old Rose may not read as having missed her chance if she is really talented.
Melissa McCarthy also reads in her early 40s at most I think. This is already a huge improvement on Babs... unless you were supporting the idea of McCarthy, I can't tell from what you wrote. :)