BVI gov't seems content in using raw sewage to fill potholes, or at least the gutters. Shameful.

Exactly...takes almost no space, you don't buy a box of way more than you use. We bring the 13 gal kitchen bags for the galley, small plastic bags that grocery stores use (I know, not everywhere these days) for the head. these are bigger than a gallon ziplock, just twist and tie. And big black yard bags to combine an keep in a hold (forward hatch on a cat)

I remember one trip we took with Trade Winds and one day I wanted to take a swim beside the boat and I was advised not to as the crew were pumping out the holding tank..and we certainly weren't any where near 3 miles from anything...closer to two city blocks. After that I took a kayak and had my swims just off shore on nearby islands.

A little late to the party here, but our recent experience was this:
sandwich size zip lock bags for each head. ALL toilet paper goes in a ziplock and thrown in wastebasket. Empty wastebasket every 2-3 days. Head stays nice and fresh.
On our own boat up north here, after using marine TP last summer, and having our heads clog 2-3 times and spending $1,000 total to have them unclogged, we're using the ziplock baggie system this year. Not putting one single sheet of TP in my heads.