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.