I was actually thinking about a transport chair - Most 12 year olds are as tall as me, and I fit ok in these chairs. They are lightweight and have small back wheels so he cannot wheel himself away. They do not have belts, but this may not be an issue for you. They are not too expensive and would give you something for home as well.
Thank you all for the help. Now here is another small issue... My husband says he shouldn't be in a wheelchair because he doesn't have a physical disability and he can walk and is fine. (no, he is not in denial about our son's disability) I am just worried about the walking off part and losing him. My husband says that since he is in regular ed classes and mostly normal in terms of all that and verbal, he should walk because he has no physical diability, it's just the noise and touching. Would your answers still be the same and what would happen with our GAC? TIA, I appreciate it.
Given the things that you added now - he is high functioning to be in regular education classes, I would also suggest a transport chair. They are light weight, fairly inexpensive and would provide what you need in terms of keeping him in place and touching.
That would be able to be brought into lines because it is a wheelchair. Or, you could use it to get from place to place, park it with the strollers and then have him walk in line.
Given that he is functioning in regular education classes, it may be difficult to get a special needs stroller or wheelchair covered. He has the understanding to stay with you; it sounds like hes missing the impulse control that keeps him with you.
Another possibility would be to use a locator system - he wears a transmitter and you have a receiver. If he gets too far away from you, the receiver goes off and you can use it to be led to him.
Orlando
Stroller Rentals also rents the Big Leap GPS locator, which can be placed on your child so that you can find him/her if they wander off. The contact information is in post 2 of the disABILITIES FAQs thread.
For the noise part, a GAC really does not help that much. The parks are still noisy outside of the lines and attractions. I would suggest ear plugs or noise reducing muffs - you can get some used by people working with noisy machinery or for people doing target shooting. Those dampen the sound down to a manageable level for most people. THe in ear kind are small and unobtrusive.
You may also find that a good touring plan is much more helpful to you than a GAC. A GAC only helps in lines, but the wandering off will not be a problem in lines - just when you are going from place to place, where a GAC will not help you at all.
A touring plan or at least being aware from things like touringplans.com which park is the green (least busy) park for the day will help everything. Knowing when to be where will cut down on both waits and crowds. Using Fastpasses and the regular lines give a much more consistent experience. With a GAC, you are never sure what the CM will direct you to do, where the wait will be or what exactly will happen.
Since your son can walk and doesnt need to wait for a wheelchair vehicle or use an accessible entrance, you would have a more consistent experience using the regular lines and Fastpasses.
In addition, if you use other members of your party to be in front and behind him in lines, you can create a buffer zone so he is only close to people he knows.
Many people with older kids with autism have posted that doing these things (touring plan, buffer zone', ear protectors specifically) was more helpful to them than a GAC and they seldom need to use a GAC. As for what to say when requesting a GAC, you would explain the difficulties he has in lines the same as you did before. Dont be surprised if they suggest renting a wheelchair because that would cut down on running and give him a place to just chill.
Other people have posted that it helped a lot to have their older child doing something - like that child has maps and is the navigator for the group. Or things like looking for hidden Mickeys or telling the group tidbits of information about that part of the park. In other words, keep him busy and engaged.
