So, I ended up going with a modified version of this recipe:
https://wilsonhomestead.com/how-to-cure-ham-without-sodium-nitrite/#wprm-recipe-container-242466

I've pretty much halved the recipe from the link, and could possibly halve it again (except for the pork and water components).

✅ Pork scotch 1.8kg
✅ Water 1.2l
✅ Salt 90g (3% of 3kg)
✅ Brown sugar 1 cup
✅ Fennel seeds ¼ cup
✅ Mixed (yellow & black) mustard seeds ¼ cup
✅ Celery stalk (including all foliage) x2, chopped
✅ Bay leaves x3
✅ Onion x1, chopped
✅ Garlic x8-10 cloves
✅ Death Powder* 1 Tbsp
✅ Thyme ½ tsp
✅ Rosemary ½ tsp

Mix all brine ingredients in a saucepan & bring to a boil. Cool.

While waiting for the brine to cool, skewer the bejeesus out of the meat (1" grid).

Brine for a week, turning occasionally. Drain, dry and tie.

Place into smoke grill, and set the thermostat to 135°C. Wait for a long time (in this case, I waited for around 7 hours all up). While waiting, start making the glaze - here's one I dreamed up yesterday:

✅ Coca-Cola¹, 375ml can x1
✅ Fermented lime** x1 whole, finely chopped
✅ Garlic x3-4 cloves, crushed

Place ingredients in a saucepan over low heat, and reduce by maybe ¼ 🤷. Brush onto the ham every half-hour, or when you remember...

Anyway, I have things to do today, so my photos will have to wait.

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* Death Powder consists of #fermented, dehydrated, smoked, ground chillies, garlic, and other sundry vegetables from last year's harvest. It is salty, sour, and spicy.

** Fermented lime is sour, bitter (rind), salty, and citrussy. If you don't have fermented lime (who does?), you might experiment with lime juice, salt/fish sauce, and maybe some bitters (see also note (¹) below).

¹ I have been thinking about replacing "the real thing" with cinotto for some more subtle -- less corporate -- flavours. Doing so might require the addition of more sugar, but this is just speculation.

@warkolm