I have a house in OCNJ and for a 5yr old I would recommend no stroller. Honestly, it gets so cramped, especially inside the Wonderland Pier. There is no where to push them. I would NEVER EVER bring a BOB stroller unless I was going to jog on the boards in the morning, every morning. And then I still wouldn't bring it up to the boards at night.
A 5yr old can walk just fine. The boards are not that big. There are 2 major amusement piers and they are 8 city blocks between each other. That will be the extent of your walking except back to the parking lot or house, depending on where in OC you are staying.
The most important things to remember about OCNJ is Manco & Manco Pizza