It's a close call, USMCR, but there is one additional element required for a DUI conviction under the circumstances you describe. There must be some evidence that the car was driven on a public roadway. So, if you were found drunk, asleep in your car parked on the side of the road with the keys in the ignition, you could be convicted (assuming you were the only occupant). On the other hand, if you were found drunk, asleep in your car parked on the back 40 of your farm with the keys in the ignition, there should be no conviction.
The point I'm trying to make is the DUI law has an implied element of recklessness in that it only punishes operating while less safe on public roadways. You can infer that the legislature believes the necessary element of recklessness is not present when driving on your own private property.
So, I think there could be circumstances where one discharges a firearm while "less safe" but in a manner that is not inherently reckless. The example I gave was shooting at a range, which may not be the best example, but you probably get the idea. Shooting inside a tavern while intoxicated probably is inherently reckless. Shooting in other circumstances while intoxicated probably is not inherently reckless.
I think criminal codes should be narrowly drafted to include only the precise conduct sought to be punished, and no others.
