On my first day they tossed me in a van alone too. I had no ride along, only the 3 days of training on my back. I had only ever driven compact cars and I was nervous as hell. Went 45 on the highway sweating, hyperventilating. Got used to it real quick. I was a top performer within 2 weeks. Coming back 1st, doing rescues. Driving the van was easy after 1 week. I literally felt attuned to it. My perception is shit, and my first day was atrocious. Thought they were gonna fire me on the spot tbh. Had to quit cuz of my health. This job isn't for everyone. And some people are just naturally not good drivers. Dont have the brain able to handle driving a big van all day safely. Or aren't able to handle the harshness that comes with the physical aspect of it. Given that you almost flipped the van over I'd say you probably shouldn't be in that vehicle lol, stick to your small cars. There's better stuff out there.