I almost always sit in an aisle seat, but not because of when I am getting off the bus. One time back in the 70's I was sitting at a window seat, and I was just daydreaming.

I felt my skirt go up, and I pulled it down while still looking out the window. I felt it go up again, and pulled it down. Then a third time I felt it ride up, but this time I looked over and saw that the guy next to me was pulling on my slip to make my dress ride up. I hit him with my soft purse, and told him to let go, but he did not let go. He looked like he was on drugs, and I was upset. I thought about what I was going to do about it, when I saw a GF across the aisle. I waved to her and got up abruptly to go over and sit next to her. He had to let go.

I was still scared all the way home, and later that Friday night. I could not leave my apartment. A few months later, a man I saw on the bus regularly told me he saw what happened and thought I had dealt with it very well. I told him I was still scared, and did not know what to do. He told me he would have stepped in and helped me if something had happened.

I never take who I am sitting next to for granted, but I don't ride the bus anymore, either.

As for your situation, I agree that it's best to give them info instead of asking questions of them first. That way, they know why you want to sit on the outside, and not be boxed in.