Gas lockers

Are there legalities regarding placement and construction of gas lockers, or merely recommendations?
The reason I ask is that I follow several small van converters online, converting mainly for the 'stealth' market, where the outward appearance of the van is basically unchanged from standard. If gas bottles are installed they're usually housed inside the van in a wooden cupboard.
To me this doesn't look very safe.
Al.

The base of any gas locker should be open to below the habitation, Propane and Butane are heavier than air so must be allowed to "fall out" if there is a leakage.

Often on boats you'll see a gas tank on the aft handrails, so if it leaks it goes overboard. last thing you want on a boat is a bilge full of gas...

My Westfalia has the gas bottle inboard but has a drop vent in the floor of the cupboard.