Need advice with separation anxiety

My mini dachshund puppy is now 5 months old and really struggles with separation anxiety. I know that this breed is notorious for struggling with separation anxiety and crate training. We got her when she was 8 weeks old and have been crate training her. Crate training was definitely a struggle, took her about until she was 3.5 months to not whine for hours at night in the crate even though she was right next to us. However we just cannot leave her without her freaking out. I think I’ve tried everything possible but just coming on here to see if anyone has any other suggestions. I started leaving her for small time increments from the beginning but her anxiety has only gotten worse. We started with locking her in the crate when we leave and we have a camera set up to watch her. She would basically hyperventilate and cry the entire time. It got to the point where she would start pooping in the cage right when we leave as a stress response (I’ve been told that this is somewhat normal for separation anxiety) that ended up being a mess so we then resorted to locking her in the bathroom with the cage in there (door open) and had some water for her, toys, high value chews, etc. this helps with the pooping issue so that she’s not covered in it but there is still poop on the ground. I’ve tried everything her meals in the cage to get her to like it, giving her high value treats in there, we even got a scent diffuser that’s supposed to help calm them, white noise, some natural “calming” chews from the vet, nothing seems to help. To this day she will cry an entire 4 hours I leave her, will be hyperventilating and will not calm down. I give her favorite treats when I leave but she won’t touch it until I get home because she’s too anxious to eat it. Like I said, I know this is common with this breed, but from what I’ve been told it shouldn’t be this bad. I know she’s still young but I don’t know what to do, it’s only gotten worse and I feel really bad for her. Some people have suggested I get another one so she has a sibling which I honestly truly think this would help her but I just really can’t afford another one right now. Maybe in a year or two but want to see if anyone has been in a similar situation and has any suggestions for me. Was really hoping to just have one dog but if it never gets better I may consider it to just keep her happy. Sorry for the long post & thanks in advance !!