perhaps set the small pots in a larger one with soil so they don't get as hot on hot days and you won't need to water them as often? Neither of those plants will stand for wet roots, they will do better going completely dry than staying wet. They both need full sun and fast draining soil.
The pencil plant is (I think) native to parts of Mexico and the ones I've seen growing wild are in the desert highlands near Oaxaca. They are trees there. It is dry, very dry, and mostly poor soil but with excellent hilly drainage. I have one here on my roof in full sun, it holds up to our humidity but I keep it in a small pot compared to its size and with fast draining soil. It never looks as good in the rainy season as it does in the dry season.
