You got pretty good suggestions on the dragonfruit varieties.
But I dont know how those do in florida but they produce well here. My trees are loaded with s8, condors, dark stars. Paloras its yet to see how they do in CA, havent seen anyone grow them but maybe theres a few out here.
Honestly you dont need huge pieces, it really makes little difference if you get a 1ft piece or 2ft piece. Its going to grow. I usually just start them from 6-8" pieces. If its hot there, they are going to grow fast either way. When I sell to others its usually 12"to 18" just because people think they need big pieces.
You can send a private message if you want to buy cuttings.