Carrying Aux propane tank

I did remove my post as it was obvious after I wrote it that I didn't have all the facts.

As you said in this situation, the tank was leaking and filling the bed with explosive gas - that was the problem. Propane is heavier than air and sits in the bed and the static electricity ignites it. The cause of the disaster was a leaking tank, not an exploding tank.

Any form of combustible gas or liquid has to be treated with respect. I would never carry a cylinder, especially a disposable one, in a compartment (vented or not) - that's the reason that the manufacturers strap them underneath the RV so that any leak drops to the ground and disperses.

Again, sorry for your loss.