I think that's a good possibility. If he didn't try to speak to her, he probably circled around once or twice before he hit her. I have a feeling Mickey sensed something was up, and running into her bike was no accident. From what we've heard about Mickey, she had good instincts. Riding alone that night, her radar would've been up. That's why I don't believe that she got into the truck voluntarily.
We don't know if Mickey was injured when she was knocked off of the bike. She might've broken a leg or an ankle. In the scene that runs through my mind, Mickey couldn't get up. She saw sitting on the ground when she saw BSL approaching with a knife in his hand. The mace was in her pocket, and when he tred to grab her, she sprayed him. BSL dropped the knife, and Mickey was able to grab it off the ground. He bent over to take it from her, and she stabbed him in the back. A struggle ensued on the ground, and Mickey got in a few more blows with the knife before BSL wrestled it away from her.
He would have been in a furor, and he probably stabbed Mickey numerous times until has rage was sated. Then he put her in the truck, and drove around planning the next step. There was no way he was going to leave Mickey behind without making sure she was dead. So, he decided on the cane field because he could shoot her there without alarming witnesses. Leaving her body in the open field was too risky. He drove to his house, and so forth. JMO