If you want a pocket RTC, you're better off looking into mid-size catfish that resemble it in body shape and behavior. Sun cats, lancers, bumblebee cats (both Asian and SA; former is more colorful, latter is closer in body form), gulpers, Chrysichthys ornatus or assorted pims will scratch that itch in a more modest (<125g) tank. If it's the showy tail you're after, consider getting a pleco like L091 or L114 and growing it to full size.
As more experienced members also said, even robust hybrids between species in the same genus are subject to deformities and potentially shortened lifespans. Trying it with a pimelodid and a mochokid is asking for a lot of dead embryos and a handful of fish in perpetual agony, that will most likely pass before they're a year old.