Now that I took a better look, lots of people grow those red Jatropha in their gardens here. I hadn't realized they were Caudiciforms.
I also have a Sinningia tubiflora that does have big tubers. It says in the description on Tropiflora's site that you can grow it with the tuber above ground as a caudex! But they have it listed as a Gesneriad.
If it ever blooms, I will show a picture, it's supposed to have lovely long, lemon-scented white flowers. I need to move it to more sun, I think.