My 2 cents on a marine toilet is no marine toilet. No holding tank, no smell, no repairs, no clean up, pretty much no nothing in the way of a traditional marine toilet
Drywall bucket. Toilet seat made to fit bucket (amazon, eBay). Roll of 13 gallon kitchen garbage bags. Box of depends. Can substitute puppy pads.
Directions. Sack in the bucket. Depend in the bag. Job in the bucket. Tie knot in bag. Double bag. Second knot. Finished.
Kiss. Keep it simple Stewart.
Entire cost for the sailing year should be under fifty dollars.
Where to properly dispose of depends sack? Anywhere you can legally dispose of any other diaper. Follow the laws in your area.
Again, no repairs, no smells, no clean outs or clean out fees. Kiss.
Want something better than a bucket? Get a retired land toilet and fill the flush hole with cement or scilcone. No need for the upper tank, just the base and seat. This is what I am doing to my head. Real porcelain pot with no headaches of marine plumbing. In my aft cabin, building bucket version into a berth. Toilet stays hidden under cushion until you need it. 32 foot sailboat with two heads and no flush plumbing to bother with.