If they ask questions about nap/rest routines I tell them at what age I try to transition them to a nap mat. If they don't ask specifically I just discuss nap/rest polices in general.

I think the biggest issue you are having with clients isn't really anything to do with any of your policies but maybe with HOW your policies are conveyed to them and whether or not these new families truly understand your methods.

For example I have a basic guideline sheet for interviewing.
I list the topics I will NOT budge or waive and sometimes bullet-point things I think will apply to potential family. Then I make darn sure I cover those topics really really well so that when they leave I am fully confident that they know, understand and CAN adhere to those policies.

I don't just say "You read and understand everything right?" and wait for them to ask any questions or mention concerns. I kind of get pushy about it. As an example I've said things like this during the tour/after the tour on the phone or in e-mail conversations with parents.

You read the section on toilet training correct Ellen? SO you understand that I will NOT take your child to the toilet every 15-30 minutes throughout the day?

You also understand that your child cannot wear underwear until those skills we discussed (also which are listed in the handbook) have been met? Oh, good!

I also want to really make sure you understand that I don't provide a grace period for pick ups or for payments due? If you are unsure of any of the polices in this area please re-read your handbook as this area is THE most misunderstood in the world of childcare and since I have some really firm consequences for these things.
I hate to implement them if a parent doesn't fully understand my policies so again please make sure you reread that section in the handbook so that we are both on the same page."

Those examples aren't necessarily the exact words I use but are examples of the type of conversations and back/forth chit chat that I make a purposeful point of doing so just some random suggestions on really making sure parents understand your policies in the same way that you intended them to.

It sounds like families like you and are interested in using your services but the issues arise from the last few parents either purposely trying to manipulate you/your policies or arise because parents don't really understand them. I am going with the latter as that seems to fit better.

Anyways, I hope that helps.