those bars look really nice. Can't have them here as I am renting - I look at having them at my new house, though.
I also thought of having either very thick see through plexiglass or a form of shock resistant glass - my main worry is them jumping on the glass and breaking it and getting hurt.
Jack does go straight to the door when someone's there and bars to call me - but it's not an aggressive bark, it's more like "look, someone's coming!". Then I either tell him C'rate" or I let him sniff the visitors, depending on how fearful they are. I don't let him around them if they're afraid, no need to stress people out. Girls are more reserved. Sophia comes to pet her when called. Luna doesn't get close to new people. She "huffs" sometimes and I tell her it's ok, girl.
I would've expected Luna to be first line of defense: it was Jack. They're all fixed now, so wasn't testosterone or anything.
I can't compare what I saw that night with normal Jack. He wasn't even barking - he was making sounds I've never heard before... There are posts on neighboring groups about recent aggravated burglaries, with thieves coming in the house regardless there owners were at home or not, and some horrific assaults, so I am so glad my pack protected us. It wasn't about the house at the end of the day, I couldn't care less about the house, it was us: my daughter and myself.
Usually, when Jack hears something at night, he sits in bed and listens. I've always found it funny to see how he moves his ears: like redirecting antennas.... Now he sprinted straight from deep sleep. So he must have gotten a really strong clue. Someone told me about mastiffs being lazy: "they don't seep. They WORK when you think they sleep." I couldn't agree more.