Are we in time?
Double strapping the hives with ratchet straps is a good move but don't over-tighten, the floor is not that strong nearer to the back and you could break it.
I always put a third strap horizontally around the hive at the entrance level to cover whatever you have blocked the entrance with.
A two hour journey? I would definitely use a travel screen and I'd take a water spray bottle in case I got held up and the bees started to overheat (spray a light mist through the travel screen). The problem with relying on an OMF is that some have a very small gap for air when sat on a car/van floor. I put mine on a wooden hive cradle I built for transporting hives to ensure there is plenty of air flow and to give me and my assistant something to carry the hive with.
Once upon a lifetime ago I did a fair amount of travel in the back of a C130 Hercules aircraft and shared a house with one of the Mobile Air Movements teams - they taught me a lot about strapping loads in vehicles that might have to stop quickly - you need to use at least two more straps to stop the hive (a) shunting forward in a crash and (b) tipping over.
Even if you double strap a hive, if you don't secure it properly in the vehicle, it is unlikely to stay together if it has slammed forward into a bulkhead or the back of some seats - and then you'll have few thousand bees joining you - so wear your beesuit and be ready to pull over the hood.
I have black straps for the hive and blue for securing in the car so I don't take off the wrong ones at the destination.
Keep the engine running - the engine vibration seems to keep the bees calm and don't rush to open the hive when it is in its new position - let them settle. One beekeeper died when he made the error of opening a hive that he had just moved (to put on a feeder) - how he missed the noise of angry bees is another question and he wasn't even wearing a beesuit!
Safe journey