I dont pretend to be a LEO or have any LEO training whatsoever but I have lots and lots of military training and no I dont mean weekend warrior...
Here are my thoughts on your list.... Please note I am NOT in any way trying to be critical of your list. Hopefully maybe I can provide at least one new thing to think about and if not at least I tried to be helpful.
1. Get to cover;
2. Deploy your long gun;
3. If feasible, wait for backup before contact;
4. Establish fire superiority;
5. Distance is your friend;
6. Run away;
7. Stop the bleeding;
8. Move laterally;
9. Maneuver on the enemy's flank;
10. Watch their hands;
1. Situational awareness - The car behind you may run over you before you can get to cover... Also the driver may not be your biggest threat just the one your attention is on.
2. Have a mental plan to get to cover and try to think as your potential adversary might.
3. Get to cover or in the absence of cover in a very short time then present yourself as a reduced size target... Turn sideways or kneel or whatever you can do to present as little target area as possible while staying mobile enough to get to the better cover. I can’t count how many videos I see officers retreating in a full stance without crouching or they are facing full chest forward.
4. Unnecessary movement can result in unnecessary exposure.... A long gun for certain is great but its not so great if your going to get shot while you move to get it..... Your mental plan should have prepared you to execute or not execute this step.
5. If possible get the long gun..
6. Wait for backup while surveying potential attacks - will the BG shoot through the back window? Are they bucket seats that make turning toward you hard or are they bench seats that arent much of a problem??? Are they still seatbelted?
7. Understand the tactical situation - the BG(s) may decide its better to take you out and attack... Your car in that case may be more effective than the long gun, if you can set off the BGs air bags with a minor collosion (I have no idea if this is legal idea so ask a lawyer but it may have a place) it may provide the distraction and the tool needed to allow you the extra moment to deploy the long gun in the face of multiple opponents and employ the force as necessary while trying to wait for the backup.
8. Fire superiority may be your friend but accuracy and shock are your the point of your spear and your armor. Nothing takes the wind out of people like seeing the most agressive BG taken out.... The shock will probably be in part your volume of fire but keep in mind rounds that leave big spider tracks in windows will have a mental effect if the engagement becomes something longer than a few seconds.
9. Distance is your friend but dont expose yourself needlessly to get distance..... Your mental pre-plan should have given you some idea of if this will be practical... and like everything else it all depends on the actions of the BG(s)..