You, know, I wonder how realistic the OP’s issue is. In my case, whatever shalom bayis issues that may have arisen in 45 years of marriage, tznius wasn’t one of them. I mean, an otherwise tznius wife doesn’t wake up one morning and decide that she wants to wear shorts and a halter top. If the issue arises pre-chasunah, no problem. If it arises shortly post chasunah, nu, mekach taos, seeyah! Shalom bayis implies that a bayis has been established. I can only see relatively minor issues arising in an established household, the kind that discussions with one’s local moreh d’asrah should be able to resolve.
For instance, the wife decides that she doesn’t need to wear a shmateh on her head in her own house when no one but her husband is there. There is clearly precedent for that view but it doesn’t happen to be the custom of either family and she’s covered her hair at home up till now. In the unlikely event that that a loving couple can’t straighten the dispute out themselves, a counseling session with the Rav ought to fixit. If not, that couple has bigger problems than hair covering.