Stazy, there is a nearby park with a very similar layout where I frequently walk my dogs. They go off-leash there, and I have seen other basenjis off leash there as well. There are no cars in sight, and the off-leash area is set far enough within the park that they're back on leash well before we ever get close to the parking lot.
I think off-leashing depends a lot on the layout, the topography (i.e., is it woodsy and hilly, or pretty flat with high visibility?), and on how well you know your dog(s). My shiba (another breed not known to be trustworthy off leash) always keeps me in sight, and he knows he doesn't have to play keepaway because off-leash runs are no longer a rarity for him. The first time he went to this park, he got so excited about being off leash, he bound over a small hill and lost sight of us. He panicked and had started to wander off in another direction by the time we followed to where we thought he was. Then we saw him behind us frantically looking around, whipping his head back and forth to find us. We called him, and he came running with his ears flattened against his head, so relieved to be reunited. That was the only scare we ever had (I think he was more afraid than we were). He's always made sure to keep us in sight ever since.
But I've found that if they run too far at a park this large, it is NOT easy to call them back with just your voice. We get lots of wind coming in from the water at this park, so that limits their recall a bit.
With Bowpi, we waited until her second month with us, always walking the same route around the park, before she was allowed to drag her leash. It became apparent that she wasn't interested in going far, so we let her roam free. Maybe it was easy with her because our shiba's a good off-leash model, and she knows she's with us. Or it's just her age and her mellow personality. She goes into little racing bursts every now and then and does huge, wide circles around us, but once that's out of her system, she's happy to trot alongside the pack.
Sometimes Bowpi gets a kick out of flushing flocks of birds from bushes, but she's smart enough to know she'll never catch them, so she doesn't chase.
We ran into a rabbit once. Five dogs gave chase, including my two, but wonder of wonders, they both actually came back when I called.
So I know it's not without risks. But given the hundreds of times we've been off-leashing without incident, I think it's worth it for my two dogs.