Stranger Aggression but only while at home

I have a 4 to 5 yr old Corso that we rescued a couple of months ago. She is the sweetest girl with us and my three young kids. While we are out in public she is well mannered and doesn’t get worked up if there are other dogs barking or acting up. She minds her own business. When at home she is extremely protective of us and property. While at home if a stranger comes over she gets a bit aggressive not towards us just at the stranger. She has never bitten but she will bark and growl. I have her on a leash and we are working on her stop comand but it’s going slow due to the fact we dont have people coming over every day.
This is my first Corso and I have been working with a trainer for the last six weeks. It took my girl 5 weeks to get comfortable enough to give our trainer kisses and be submissive towards him. My trainer has worked with a variety of breeds and used to train Police K-9’s so I feel he is well suited for us. He does have a vast knowledge of the Corso but hasn’t worked with too many of them.
I’m looking for any other ideas on ways to help our girl become less aggressive with strangers while at home. Once she meets them she is fine and will love up on them but always has to put up a show to intimate them first. I’m not allowing her to do so I do correct her behavior when she is acting aggressive but as I said it’s coming slow and wondering if there are any other techniques to try? TIA!