Alkaline batteries are very reliable, just replace the batteries every 2 or 3 years to prevent them from leaking if they are not used.
I have a 4x AA headlight in the car, it will only be used for emergencies, and i replace the alkaline batteries every few years.
There is a piece of plastic between one of the contacts of the batteries to prevent them from draining (that headlight has an electronic switch and there is a very small current drian when it is not used).
I use these and never had problems with leaking cells:
https://lygte-info.dk/review/batteries2012/Aerocell%20AA%20UK.html
These Aerocell AA are only 1,99 Euro for 8 cells (Lidl).
So it is only 1 Euro for every 2-3 years that the headlight stays in my car next to the spare wheel.