The RP aspect of the idea is nice, more importantly for the capital classed ships of cruiser and larger.. And the Decay part wouldnt be too hard to put in.
The best way to get people to use it though would probably be to have it sold at every planet / station base at a fairly cheap price (ex: 100-200) and remove it from the Ship Bases (ex: Rogue Destroyer, Battleship Missouri) as a ship wouldnt be selling its own fuel, would it?
The infocard as it is doesnt say its perishable. In the select_equip.ini
decay_per_second = 1
can be added to HFuel, and in that same section set its HP to lets say... 300.
That makes 1 HFuel decay after 5 minutes.
20 HFuel would last 1 hour 40 minutes