I've placed my order, as follows:
Kildwick Kompact Urine Separator × 1 £45.00
Eco-Loo 'Quiet' Fan Kit - 12v × 1 £20.00
20 litre Solid Waste Container × 1 £8.95
12 Litre Urine Container - translucent × 1 £34.00
BioBag 25 litre Compostable Bag - Roll of 25 × 1 £8.49
Eco Urinal Blocks - Pack of 10 × 1 £7.00
Subtotal: £123.44
( to this must be added a standard household toilet seat in solid wood)
I reckon I can make a much more compact arrangement by building in an enclosure as part of the boat, rather than trying to fit in any of the proprietary fully-built units. My problem is headroom, and this seems to be quite a good solution, as the urine container is low (but quite large). I have plenty of room fore and aft, and that's good, because I will need a container of composting medium readily available.