Hi Chris!
Welcome to the Disney Parks Moms Panel! This is a great question, and I have just-as-great news that I think you'll like. Yes! Guests may leave and re-enter the same Walt Disney World Resort Theme Park as many times as they'd like in a single day even without a Park Hopper Ticket!
This is actually a very popular way to spend a Disney Day as it gives you a chance to rest, cool down, eat not in the parks, and come back fully refreshed and ready to play throughout the evening. My good friend and fellow Moms Panelists Tabitha builds a few hours into each of her park days so her family can go back to their
Disney Resort Hotel to let her kids swim out their energy and then recharge with a quick nap.
I like your plan of leaving Magic Kingdom Park to eat at
nearby Dining Location. You'll be able to quickly access the dining locations at Disney's Polynesian Village Resort, Disney's Grand Floridian Resort & Spa, and Disney's Contemporary Resort via the
world famous Monorail. Or, you can hop into (more like carefully board) a
complimentary Water Taxi to reach the above three resort hotels, as well as visit Disney's Wilderness Lodge and Disney's Fort Wilderness Campground.
You don't even need to get your hand stamped, Chris, as your ticket will auto-Magically remember you from earlier in the day.
I hope this helped better plan your Walt Disney World Resort vacation, Chris, We'll See You Real Soon!
~Kristen