I have cooked many hours on my Camp Chef stove. When slid all the way out from the rig I have over 5' clearance and there is no way that it is more dangerous than doing the same cooking inside the rig. I have never had to clean up any grease from the side of the camper. It is true that if you were cooking directly under an awning, you may eventually have a grease issue, but I haven't seen anyone do that. My Camp Chef stove is 30,000 btu rated with 10,000 btu per burner. I use a two burner griddle, along with the bbq grill and I also do dutch oven cooking on it. I can't imagine trying to do the same type of cooking, in the same timeframe, on the inside of the camper. Besides, my 3 burner interior stove won't put out anywhere near the same btu capacity. I can, and have, filled the entire griddle with bacon, when cooking for a large group. Can you imagine what that would smell like if I was able to do that on the inside?
On last years Montana TC rally I cooked three 12" dutch oven cobblers (with the tents) on that stove and it worked very well. I certainly couldn't do that indoors. When set up properly, a high capacity outdoor stove system will outperform any interior stove that I've ever seen in an RV.