Greetings

First, is there any particular part of StL that you desire to be 20 mins away from? Are you talking downtown, airport, etc.? In any case, as you are probably aware you can be to, for example Union Station area in ~30 minutes from Highland/Troy. Some very good info will hopefully come from CellarBelle... she is in the Edwardsville area, and even tho' she is in IL, I forgive her as she is a rabid Blues fan too.
As to the StL "crime ranking" - ignore that BS, and instead be aware of yourself when in 'specific' parts of the area, esp. during darkness. And yes, the numbers are indeed skewed, as they do not take into account the entire metro area - just the StL city numbers. Matter of fact, the FBI discourages people from even giving any credit to that ranking - many variables are in play when trying to compare this and that city. However, even w/ that said, I would still be leery and cautious when out and about in certain areas.
Good luck!