@Connie-And-Eric0 You should be able to customize trip lengths for any specific period of time, i.e. Thanksgiving, Christmas, special events etc. When you go to manage your listing under Trip Length click on Add Another Requirement. There you should be able to designate dates for which you want a custom minimum night stay. I know of no limitations on this.
If you are not sure your custom minimum night stay is set correctly, tell me what dates you have tried to set a custom minimun night stay and what that minimum is. Also tell me which listings if they are not the same. I'd be happy to check it out for you.