I haven’t seen one fitted but there’s a former Weta owner who fitted one here
There’s a reinforced area at the base of the mast and a bulkhead just in front (towards the bow).
I think you’d be advised to fit an inspection hatch so you can use bolts to secure the base rather than screws. You can use a regular 6″ hatch but for something larger and more waterproof, I’d recommend a Kayak hatch.
If you need more assistance, I’d suggest sending an email to firstname.lastname@example.org for instructions.