just thought I would expand my experiences if you don't mind. I used to have a Liberty 23 with a large head and used a Thetford 165 which was around 400 mm seat height. The Jabsco manual is 330 mm which is what I have in the Baycruiser 26.
In the 20-30 years I had the Liberty I emptied the toilet once a year and it smelt once. That was due to a problem I had. I emptied down the toilet at home. Most of the time I used a bucket for peeing and waited for shore for the rest. I primarily stayed in marinas whilst away with the odd mooring and anchor.
I would not get a Jabsco type as urine mixes with salt water and solidifies. If you use it a lot then after 4 years you almost have to replace the pipes and clean the holding tank. Excessive pumping as per a previous post works really well but in the end..... The smell comes from the inlet surprisingly and there is a system on the market which completely removes the smell -
https://www.seasmartmarine.co.uk/index.htmlI have a friend who swears by it. I investigated a fresh water feed for the toilet which resolves all the issues but there is a chance of contamination so stopped that approach unless I installed another fresh water tank - no room for that.
When I replace I will go for the Kildwick DIY Kit camping toilet MicroLoo composting toilet. It is the same height as the Jabsco. By keeping the urine and poo separate you stop the creation of sewage. You can chuck the urine over the side when it fills and the poo goes in the bin when you get home as it is not treated as sewage or of course put it on your garden as compost. It is good for a week and just carry spare bags if you go further. Women have to learn how to use it apparently and you have to sit down as it relies on separation as all compost toilets do.
The easiest route would be the chemical loo (apart from the emptying) and the most ecological the composting loo and the marine loo - I would forget it.
Hope this helps.