OK, I may be not the best advice giver since I haven't seen live bass of any kind but theoretically I may try to tell you about the life of goldfish (crucian carp).
In case you don't have any predators then after a few years you will have pond full of small crucian carps. They breed often and have lots of baby fish after that. Adding some amount of perch doesn't help a lot - because of their mouth size, they can eat only smaller ones while the large ones breed and breed. Pike is the only solution - it's mouth is large and it grows large itself (and it eats a lot).
In your case largemouth bass could act as a pike because of it's great mouth size. But what about smallmouth bass? Will it be able of eating anything but a tiny ones? Since your pond isn't big, bass probably won't grow very large too. And don't forget that little bass needs other food than live fish and crucian carps will compete with them for the same food...

OK, after some beers maybe it is not the smartest idea to talk about fish but the main idea is - CRUCIAN CARP CAN EASILY GET OUT OF CONTROL.