You sound like you're figuring it out fine! I don't know how many birds you're feeding or how quickly you will go through it, but as long as you keep "feeding" the bucket periodically with new, dry food and water then it shouldn't spoil. Even in the heat. My husband kicked ours out of the shop because he really doesn't like the smell. So, ours sits on the back porch. For several hours in direct sunlight. The heat, IME, helps the ferment take place quicker. I really don't think it can go bad. If you don't stir we'll, then the stuff at the bottom will get extra fermented and smell stronger, but it's not spoiled per se.
Please note: you will see a film develop on the top between feeding times. Depending on what you're feeding, the film may be beige or grayish or white. This film is not bad mold. Don't worry unless you start seeing green or black stuff growing in there. It WILL smell strongly too. Some people (my husband) think it smells "rotten." Others (me) think it smells sour, but it's not a rancid smell.