Looks absolutely beautiful!
I would really like to hear more about that self-designed/built urine separating composting head you referred to! We're about to take the leap on a commercially built unit (Air-head) but am fascinated with the aspect of building one myself to better fit the available space and eliminate the excessive hight of the commercial units.
1973 Chance 32/28 'Westwind"
C.f. Privy 500 - Upgrade your outhouse
Add a fairly airtight container to house the bucket, with air circulation. I use a small computer fan connected to an auxiliary house battery, run 24/7, where the battery is kept topped up by a solar panel -- though many folks use a Nicro day/night solar vent. Pretty simple, really.
A second bucket with tight fitting lid provides a means to rotate the composting waste prior to disposal, since once a bucket is full, it still needs a month or two to fully compost.
For the enclosure, I went with a teak box intended for a hallway or similar, to match the teak already in the head, something close to the following:
to which I added boards internally to make it relatively airtight. You can of course just build a simple wooden enclosure for the bucket.
I reused the toilet seat from the Lavac toilet I removed.
Even with the teak box and ready-made separating insert, the cost is *alot* cheaper than the ready made Airhead or Nature's Head toilets (not to say they aren't quality products, etc.). If you have the time and are handy, you can get an equivalent solution for a fraction of the cost.