Hi Karen. When you add the Park Hopper option, it actually covers all the days that your ticket is valid, so you won't be able to just add it to one day, unless you've purchased your tickets individually. I highly recommend adding the Hopper if possible because it's really nice to have the flexibility to bounce between the two parks, especially since they are situated so close together! Here are some ideas that might help, if adding the Park Hopper is not an option:
Disney Studio 365 is located in Downtown Disney and does not require park admission. Although the styles here are geared more toward the "rock star" princess, there may be a look that your little one will love! My daughter actually prefers the makeover packages at 365 to those at BIbbidi Bobbidi Boutique, and you can always buy a tiara in the World of Disney Store to incorporate into the hairstyle! The stylists here can create the most unique and over the top coiffures including our favorite, in which the hair is wrapped into a big bow on top of the head! You're little one will even be able to choose her favorite colored hair pieces and pixie dust to really make the whole look POP!
You could purchase her princess attire á la carte prior to your vacation, or you can visit World of Disney in Downtown Disney, to purchase the exact dresses that are used in Bibbidi Bobbidi Boutique. There is even a fabulous face painting cart in Downtown Disney and they offer a few styles that are perfectly suited to princesses, complete with a crown painted on the forehead and lots of glitter!
Creating your own princess makeover eliminates the need to enter Disneyland not to mention the fact that your little one will have a look that is totally unique and original!
If you have any additional questions, please don't hesitate to ask me! -Amanda F.