Realistic conditions for fuel container explosion
The topic of explosives in movie production is a specialty application as one does not generally employ classic explosives!
In movies, the aim is NOT to kill/injure anyone (especially, your famous lead actor). As such, one can select even a flameless explosive, which, for example, could include Ammonium nitrite ($\ce{NH4NO2}$). The latter is primarily a pressure explosive which, per a chain reaction, quickly releases a massive amount of gas. Such explosives find applications, for example, in blasting in coal mines. Apparently, mines can develop a potentially explosive mixture of methane and air, where a flame/spark could result in a massive secondary explosion!
Also, distinct from a battlefield setting, consider low brisance explosives, which do not produce lethal shockwaves.
In essence, your objective should differ significantly from the design/use of military-grade explosives. Instead, aim at much flash and dust, but less lethal. The sound level of the explosion can be addressed in the post-editing of the film.
To accomplish this, you need more research and the opinion of someone who actually specializes in this area.