Theoretically it's a good idea. Here is a possible problem. You say you want it to be open to the public and that you want it to not have as high a level of competition as "regular" race servers. Well, I can tell you that we allow a tremendous amount of competition in our servers and still find it difficult at times to keep guests self disciplined enough to not have chaos. To try and run a server where you force even less competitiveness than in "regular" servers is going to be next to impossible. Once the guests come into the server they will do as they please and while you can feel free to kick any guest who is being too aggressive or not following your rules, that is time that you will not spend in "training mode"...and it may be a lot of time. This is one of the reasons we have one server that is always locked down. When our trainers want a place to teach some of the finer points of strategy, they can do it without worrying about having to admin. You also have to take into account the fact that there is only so much training you can do in a calm server. Real race servers are not calm!! At some point you simply have to jump in there and get some "on the job training" in real life conditions.
So basically you have a very good idea. Just be prepared to have to experiment a lot to find out how it is really going to work best to accomplish your goals.