i installed a small safe in our Class C 7 years ago shortly after buying the coach. It sits in the back of our small closet, waist high and is easy to access. I through bolted it using large ss flat washers and 5/16' double nutted bolts. Could someone with tools and time get it out... probably but it will be a PITA and require making a lot of noise {mostly the profanity from the thief}. :B
When traveling in gun restrictive states like California my pistol rides in the safe {the rest of the time it is always within arms reach as I have a carry permit with reciprocity in 37 states} but I know that my wife can retrieve it in about 30 seconds while I am still behind the wheel as it has four keystroke access should we need it quickly in an emergency. We also keep cash, passports, electronics etc., just about anything a quick smash and grab their would be seeking.
I can't imagine not having the safe as we travel extensively and are often well off of the grid in remote locations.
:C