You can also disconnect the toilet and place the tank high above with a long downflow pipe and a donut connection. Old toilets were arranged like this to provide extra pressure to flush with a chain on the handle that hung down. It works for cramped WCs as it gets the tank out of the way.

This will let you use a regular commode and not the commercial ones that require a much bigger supply line. Your toilet flange might need to be changed but thats fairly easy.

edit: 10" rough-in toilets exist and are great for small spaces. That's all I install now and I love the space it saves.