Minimum ABV to distil with botanicals in the boiler?

[wow400]

I'm in the process of doing some decent neutral to turn into gin soon.
I like my gin strong & bold so am thinking on putting the botanicals in a bag & hang it in the boiler (away from the elements to avoid scorching), rather than using a gin basket in the vapour.

A quick question - if I've got a 50l / 15 gal keg, & it takes 8l to cover the bottom element. What would be the smallest batch of gin I could make?
I've had a good search & a think and I cannot for the life of me think what would happen if I had say 2l of 94% & 6l of water to get up to the element.

Do I need a minimum ABV to get the botanicals to impart their flavour which would affect how much water etc?

I don't want to use all my decent neutral on various gins that aren't that good.
I probably should make / get a smaller pot still but it is what it is at the moment!

Kind regards,
Nic