I think that spouses that are not Hmong don't follow the tradition of bowing down. They getaway too easy!
But I believe that if you don't want to bow down you shouldn't have to. Parents from both sides will have to understand, but it's up to the couple. If they want to keep it traditional or pass that up it's their call.
Hmong marriage should NOT be about the Parent's respect and how noble they are, but the respect of love from them to their new son-in-law or daughter-in-law. They should respect the newly-wed's wishes! Parent's need to humble themselves and stop that tradition.
It shouldn't be all about "bowing down" to the parents and dab qhua in a marriage.