I'm not sure that this is the same device in the photo, but it has similar characteristics and it's made by the same company. Please note that the specs are for the transformer/power supply that you are removing from the circuit, not the LEDs that remain that you are interested in connecting directly to the 12v
DC in your Airstream.
Depending on how much you paid for the device, personally, I might try connecting it to 12v
DC. From the table, I'm guessing like the 12v rating is without load applied, and 8.5v is at the rated current. It might be worth a try, if you are willing to risk ruining the LEDs. However, I'd make sure you have an appropriately sized fuse inline with the 12v DC source, in case the LEDs short out. In most cases, LEDs (being semiconductors) just open up when they burn out (as opposed to shorting).
Obviously, you assume all risk in this experiment; and returning device for a refund or exchange evaporates the minute you make this mod and plug it in.