I have had to carry a few hives and swarms in cars and vans. Thank you for talking about the 'parallel frames' to the vehicle. It never occurred to me!
I have taped the entrances, but have found that you have to be careful not to leave exposed 'sticky bits' on the inside of the hive.
I have had a couple of funny bee-escape incidents. One involved a swarm, that my not so enthusiastic partner helped pick up. Obviously I had reassured her that all would be fine. 3000+ bees.....in a box, wrapped up in a curtain. What could possibly go wrong? Fifteen minutes from our destination my partner (driving) said she could see a bee.....and another.....another.....okay at LEAST 10 bees. Little devils! Before we knew it there were MANY bees. Our fifteen minute journey took about FIVE. She was out of the car faster than I could say jenkinsbrynmair. We never got stung....I had tried to calm her, by saying that the bees were not going to sting us, as they just wanted to be with their queen.
This was many years ago and there have been many other incidences where she will 'never forgive me.' Thank goodness we don't actually live together. I have a bath full of re-processed frames at the moment, soaking in soda crystals!