"Stand your ground" is not an actual law in OK. But, the term refers to being able to stay in your dwelling, occupied vehicle, business, or residence and not fleeing when confronted by people trying to gain access illegally or who are in your home illegally.
"Stand your ground" does not apply outside of your residence, business, occupied vehicle, or dwelling. In other words, just because you are standing on a piece of ground, does not give you any additional rights to engage. By law, you are legal to pull and use your gun if 1) you are in imminent danger of death or great bodily harm, and 2) in self defense, and 3) Reasonable, and 4) Necessary, and 5) Your actions would be deemed REASONABLE under the circumstances and conditions at the time by the DA and/or a jury. Nothing in the law justifies you pulling and using a gun to 'Stand your Ground' outside of your residence, business, dwelling or occupied vehicle.
As for the example, I would think the action that would keep you out of trouble is going inside the RV. Then, if they attempt to access (or break in) or do break in then the law says that you can assume, by their actions, that you and whoever else is in the RV are in imminent danger of death or great bodily harm and can legally defend yourself with the weapon.
Shooting a warning shot - may or may not work out. One bad outcome is if they were armed and you pulling your gun, displaying, brandishing, pointing and shooting your gun MIGHT be all the reason they need to pull their guns and shoot you. In others words, they see the gun coming their way, they can't read your mind and tell you plan on firing a warning shot, all they see is a gun coming their way, result they pull and shoot to defend themselves.
You might want to read that part again..
More than half of the states in the United States have adopted the Castle doctrine, stating that a person has no duty to retreat when their home is attacked. Some states go a step further, removing the duty of retreat from other locations. "Stand Your Ground", "Line In The Sand" or "No Duty To Retreat" laws thus state that a person has no duty or other requirement to abandon a place in which he has a right to be, or to give up ground to an assailant. Under such laws, there is no duty to retreat from anywhere the defender may legally be.[1] Other restrictions may still exist; such as when in public, a person must be carrying firearms in a legal manner, whether concealed or openly.