I retired at 51 and my wife took 3 months leave from nursing in the winter and we lived in a trailer in the S.W. during the winter months for 15 years. RV's are cheaply made and easy to get into. If you are going full time I would certainly find a way to bolt a safe to the floor maybe under a bed or in the basement of a motorhome if that is what you are using.
Now with this being said in the 15 years that we lived in our RV in the winter we did not have one problem with theft but we stayed in RV Parks where other folks are doing the same thing and they keep an eye out on things.