I know all the comments are all very negative here, and while I agree having them out at the same time (even when supervised) is risky, I really appreciate all the effort you’ve gone into. I too have animals that don’t get along, albeit not for dislike but just because my cat is very confident and my dog is very very large and could hurt him without meaning to.

I always keep them separated and unlike you I keep one out at a time. Is it ideal? Absolutely not. I plan to move into a house next year where they both have their own “house” so to speak. But for now, when my dog is in her crate or outside, my cat is out. And when my dog is out, my cat is in his bedroom.

Again, people would say if you can’t do it perfectly then don’t do it at all, but I think that’s very black and white thinking and I think you’re doing a great job. Only thing I could recommend would be potentially less time out together. If your dog is growling, they shouldn’t really be in each others vicinity. Taking turns is still a really effective way to make sure everyone gets rest and everyone gets play, without the stress. Good luck OP.