Just leave the tanks unheated, collect as much info from your surrounding areas and that will set you in the right direction for your set-up on tank design, also do alot of collecting from your local waterways in the areas where you catch your natives such as plants and rocks etc.. Most of the time you will collect the food for your sunfish on plants and at the same time you can weed it down onto pellets or such.
The main point is to have fun!