I don't know how much pressure a drum would have to safely contain, but totally sealing one and parking it in the Arizona sun for the day sounds like a recipe for disaster... :
Fuel storage and handling can be a major problem if not performed correctly. Many excellent fuel blends are allowed to deteriorate due to improper handling.
The general rule is to treat high quality race fuels like champange; keep them away from heat, light and air.
In a drum, heat will cause a rise in pressure in proportion to the RVP and temperature. Since the pressure will apply against the entire surface area, you can multiply the pressure by surface area to see how much force is trying to rupture the drum. Never allow a drum to stand in direct sunlight or even in an enclosed trailer that is not properly vented.
A partially filled drum is particularly subject to the effects of heat since the lighter fuel fractions will evaporate into the drum internal air space. When the drum is opened, a loud hissing sound is apparent. That is the sound of money and performance escaping. A fuel blender goes to great lengths to put and keep those light fractions in the fuel.
At about 100F, fuels will be to slowly oxidize forming gums that will end up on the carb surfaces.
Light exposure is only a problem when translucent fuel jugs are exposed to sunlight. Ultra-violet light will cause the TEL or TML in a fuel to decompose and produce a lead precipitate. Now you have lost (or severely reduced) the octane properties of the fuel. Unleaded fuels are not affected by sunlight. You can test the concept by putting a leaded fuel in a glass fruit jar and placing it in direct sunlight for a few hours.
Air exposure, as in open containers, will cause fuel evaporative loss and with some fuels, moisture absorbtion. Fuel is composed of heads (lighter fractions), bodies (middle fractions), and tails (heavy fractions). Each has a role to play in the performance of a fuel.
The light fractions evaporate easily and are the igniters the make ignition easier. The middle fractions contain most of the octane of the fuel. The tails provide fuel economy and some octane value.
If a fuel is prone to pre-ignition, it would be possible to drive off the light ends. But it would be difficult to know when to stop. It would much better to obtain the proper fuel in the first place. Or to work with a competent fuel blender who could use the proper fuel components to blend a custom fuel that is suitable for the application.
As in interesting sidebar, all gasoline fuels contain virtually the same heat energy per pound of air burned. Yet they may produce significantly different performance in a specific engine. It really depends on how the fuel is burned. Our job as fuel tuners is to give the engine what it wants.
And all engines, just like women, are different.