We always kept a "GO" bag near our front door in case of fire - easy to grab. At night we put it in the bedroom ready to toss out the window. We took it with us when our 'home' went in for servicing. We took it in the car when we were out siteseeing, especially while boondocking miles from anywhere. It became a natural thing to move around and ready to grab.
It contained our up-to-date computer backup (another copy was at daughter's), some cash to get us started immediately, Passports, birth certificates, a list with phone #'s for immediate contacts - insurance, excess medications that aren't in our daily pill boxes, and our wallets and cell phones were dropped in each night, etc.
A hidden safe would do no good in a fire...not enough time to access it. RV fires you only have minutes.