Trailers come with fire extinguisher as standard equipment, but at least on all the trailers we’ve owned, they tend to be rather small.
The factory extinguisher in our Rockstaff 21DS/2104s was rated 5B:C, which means it’s good for small flammable liquids and electrical fires. It’s not rated for trash, wood or paper. It will put out a small grease fire on the stove, but not much more.
Following my wife’s “bigger is better, darling” lead, I installed a 3A:40B:C fire extinguisher. In addition to being rated for flammable liquids and electrical fires, it’s also rated for wood fires. Since the inside of the trailer is largely made of wood, I will hopefully have enough fire power to smother the flames to at least get safely out of harm’s way. I mounted it on the floor near the door, directly below the factory extinguisher.
Also next to the door, I installed brackets to hang a D-cell Maglite flashlight. It’s in a handy location if we need to check something out or escape the trailer in the middle of the night.
Above it is a cup holder bracket into which we can stick a bottle of bear spray while we’re in camp. Haven’t needed it yet, but if we do, it will be easy to find.