For starters I can relate and am co-owner of a specialneeds parent group that has escapee children. It is very difficult to keep them from running. My youngest used to take off out of the house any chance he got. We had locks upon locks. I have friends who's children do the same thing. I care for a boy in my childcare who if he gets the chance if off like wildfire. There are sights for service dogs and the cost is around 1000. You can get your child a dog and have him trained the best ones are Golden retrievers and Labradors. I can go through the sites I have and send the ones on to you about the dogs. Some offer scholarships but it entails allot of work. They have been proven to calm the children and keep them safe from such things.
Is your child verbal? Do you use visual aids to help her understand her bounderies? Our children don't learn things like others and it will take you some time to help her understand. Some may get it others may not. But I have found from talking to other people and friends that as they get older they mellow more. My son did, he still wanders but he is older and things much easier now then when he was younger.My youngest was almost killed when he was 2 he went full force for the road and I grabbed him the moment the semi passed. I tell you I lost it. From that day on I made sure I did whatever I have to do to make sure my babies were ok. The slept in my bedroom till they were almost 5 snd 7 yrs old. I was a very light sleeper and would lock the bedroom door. People don't have any idea the fear we live with. It is so intense it makes you ill sometimes. So pay no never mind to people who judge you and make you feel bad. WE have to keep our kids safe.
My boys are older now and have cell phones , we have them restricted but they have GPS so if we needed to find them we could. This give them more freedom but they are always a call away.
If you are in the area give me a holler and we can get together. Just let me know.