Jason, the problem with dog parks is that people want their dogs to be little humans who need to play with other children and get along. While some do, dogs/wolves/canids in general developed only with a pack.. outsiders not welcome. In a pack, you don't like another one, you can fight or one move on (not uncommon!) and find another pack or go it alone. Some dog parks make separate fenced areas for small dogs, some allow you to sign up for an enclosed area where just your dog(s) or you and a know friend(s) dogs play off leash. But simply open dog parks imnsho are far more dangerous than they are beneficial to most dogs and definitely for ANY dog with ANY dog aggression.
The second problem with dog parks is that even if you have a dog that gets along with others, folks come in with dog aggression issues that can ruin your dog or hurt others. If your dog is not very dog social and safe, be a good owner and keep your dog out of the park. It really is that simple. If having a dog that likes the dog park is part of YOUR need, maybe you can adopt a golden or something.
As for your 2 getting along because they were raised together… no. It may help, but you'll hear from scores of owners who will tell you that it MIGHT help but very often does not. As is said here often, it works til it doesn't. So be prepared that one day you may wake up to a dog fight and you'll have to keep your 2 separated. That is simply life with basenjis.