Thousands of volunteers carry o2 in there pov's (alot of agencies allow it, always go with what your boss says) and I haven't read/ heard of any LEGAL trouble resulting from it. We leave oxygen in the ambulance 24/7 365 for the last 40 years in 100 degree plus heat. If takes quite a bit more than baking in the sun to have those o2 bottles explode.
and the bag is the best way to go.
All protocols and legal issues aside, if you haul it make sure it's secured. The other guys are right, haul it in a bag for convenience and safety. If something were to knock the head off that tank, you've got a missile in your tool box. Just my $0.02.
I live in BTR and have carried OČ in my PVO off and on over the past 30+ years. It will store just fine in your tool box. The main issue it not to allowing grease, oil, and other contaminate the set. I used the old style Robert Shaw box and never had a problem.
As far as legal. The department has to be aurthorized by the department's medical control (doctor) to use OČ, and they must have a perscription on file with thier supplier, but I know of no law in Louisiana that prohibits qualified medics form carrying OČ in thier POV.