Hi Arlo! Thanks for dropping by planDisney.
It's great that you've made yourself aware of
Park Rules and Regulations, so you don't arrive and have the unmagical experience of having to return a prohibited item to your car or hotel. The current maximum length of a backpack, bag, or suitcase is 24" long, and it sounds like your carrier exceeds that by a few inches. All persons and bags are subject to screening and it is up to the discretion of the Cast Member at security whether or not a bag can enter the parks. Keep that in mind when making your decision and selecting a carrier or a stroller.
I understand not wanting to navigate the parks with a bulky stroller. They can slow you down and get in the way of other Guests. But little legs get tired! To balance this out, strollers have maximum dimensions to help deal with the problem of lots of big strollers in the parks. My family's preference is to use an umbrella stroller. They're affordable and small. It isn't our usual stroller but it gets the job done for our vacations, and if it is damaged on the flight, we're not brokenhearted about it. You can also
rent a stroller outside the Main Entrance if you'd prefer not to lug a stroller from home or don't have one that fits within the regulation dimensions.
You're going to have a spooky good time! If you're not already following the
Disney Parks Blog, check it out. It's got all the official updates on the hauntingly yummy treats, sips, entertainment, and more you'll encounter during your visit. My must-do is the attraction overlay
Haunted Mansion Holiday in New Orleans Square in Disneyland Park. Put your must-do list together before you arrive so you don't miss a thing.
Have a magical time!
Elizabeth