i think it will work, the only problem is the otos stripping down all the algae and later starving to death if it doesnt accept the food you give it. I would say no dont do it because of tank size.
Well, I went to the LFS and alas, only one Oto. He's larger though, so I didn't mind. So far, so good. Darn, they can be difficult to find in the tank!
Thanks for the clarification between SAE and CAE max size echoofformless.