Thanks for the additional information. It is helpful.
First get a good aluminum square bar type crate. They are often referred to as empire crates. You can see one here:
They are escape proof and due to the shape of the bars less likely to cause any injury to the dog if they try to escape. It is good if you rotate her toys in the crate. I recommend no bedding and indestructible toys like those Kong makes. You can fill the kong toys with yogurt or peanut butter that does not contain xylitol . You can freeze it and give as you leave to keep her occupied.
You did state she goes out 4 times a day but didn't really mention walks. Just like any large dog, she also need to have walks to keep her stimulated mentally as well as physically. I recommend some fast paced 30 minute walks. This will help tire her out. This isn't for her to eliminate but for exercise. So don't stop and let her sniff around. Stop partway through the walk to allow her time to eliminate.
Different dogs need different methods of training. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions. This is a method that I use when training.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
In addition to basic obedience training, I would start her on agility training. She has all that excess energy to it might be good to use that for agility to keep her stimulated both mentally and physically. The following site goes over agility training and tips.
At 20 months she is still going to have quite a lot of energy. Most large female dogs start to settle down around 24 months but smaller dogs often take a bit longer. I would think you have probably close to 9-12 months before you see her mature into a full adult and calm down a bit. If you channel that energy now into an activity like jogging or agility, you can get her calmer soon as she will have an outlet for that pent up energy.
Additonally, with the obedience training you can have her sit before opening the crate and waiting a few minutes before claling her to you and rewarding her with a treat for her good behavior. I favor hot dog slivers as you can get 30-40 treats from one hot dog and they coat your hand with oil which keeps your dog interested in you and obeying your commands.
She will be calming down soon but with the suggestions I've made, I think you will see positive results even sooner.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.