Cravings while writing

I'm an academic and have an article due fairly shortly. When I'm writing, I sit in my garden and chain-smoke. I quit about a month ago and am generally fine except for when I'm working - this is starting to be an issue as it's both a) impacting my productivity and b) wearing my willpower thin. Also of note: I have ADHD and am medicated, and the first few hours of my medication are when I work best - they're also when the cravings are the strongest.

Things I have tried:

- just sitting in the garden to write without a cigarette. Cracked/bought a pack almost immediately (this is what did my last quit in - I was absolutely fine for a week and as soon as I started working it was game over.)

- working indoors. The best solution so far, but very fidgety and anxious and not getting work done as I need to.

- working without medication. Significantly reduces cravings, makes working almost impossible.

- working in the evenings. Accomplishes nothing, makes me want to cry.

- chewing gum. Probably the most effective, but jaw fatigues after a while.

- snacks. Very bad, just end up munching my way into larger trousers.

Any suggestions/anyone manage to work through the same? I'm at the point where I'm tempted to buy a zero percent vape just to have something to chomp on.