I have four sets, unfortunately cannot remember where they are....
The "hidden" set is inside the trailer accessible through one of the appliance access doors, but hidden from view. So, one has to know where to look to find the keys, and must have the proper tool to reach them. I have a duplicate set in the TV, one set in my purse, and the active set is usually around my wrist with one of those expandable wrist bands.
I also have an alarm system on the trailer door, not so much to prevent a break in, but so i can nap with only the screen door closed, and if this is opened the buzzer will awaken me and potentially scare intruders off. The "alarm" system will be supplemented by appropriate stickers on the trailer suggesting a system is being monitored by a security system off site.
A dog barking inside the trailer will be hooked up with a highly varied pattern, and if someone disturbs the trailer as in a break in attempt, this will be set off. For sure, criminals do not want a dog encounter as this is so unpredictable and that is not what someone breaking in wants. They have high control needs, so an unknown threat is almost always off-putting to them.