Danny, you are talking about a gravity fed fuge? You still need a pump for that. The plumbing is slightly less complex but accidents can still happen. And definitely more reliable than a U-tube overflow.
Billy, it is possible to culture copepods. You will want to culture a very small strain of copepods for the adults to readily see them as food. (They CAN eat them, they just don't sometimes; their wild diet is very, very tiny crustaceans.) Keeping a long term clean culture is a significant project, but is do-able if you are meticulous. If you decide to do this, I can refer you to someone who can sell you a clean starter culture.
Alternately, mandarins can be trained to eat a frozen diet. However, this training is pretty tricky and their frozen diet must be very varied and enriched with a good HUFA supplement. Many people fail at training hard-to-train fish like this one.
Honestly, I wouldn't tackle the project. It requires a level of dedication and consistency that you don't know if you have yet when it comes to this hobby. People come and go from this hobby and the fabulous dragonettes are one of the big draws. But you don't know if you are going to be happy with the hobby long term, or at what level you want to work at it yet.