Not sure how many are in your group or what your situation is (strollers, wheelchairs, etc). Uber is very inexpensive for such a short trip and would allow you to use your ART passes later in the day. The walk can be done but you will regret it later in the day (speaking from personal experience). I'm guessing you don't have an AP that includes parking because you would not be eligible for a magic morning. Uber will be cheaper than paying to park at any Disney lot and taking the tram. You could walk to the Toy Story lot and get on the shuttle. If you cut through the cast member parking lot its not TOO far of a walk. For me, I would take Uber or Lyft. They are plentiful around the park so they pick you up quickly. My wife and I have AP and fly in from NorCal and stay at WM Anaheim 5-6 times a year. We take Uber from airport and ART from WM.