What is the orientation of your unit? If it’s mounted vertically on the wall then the beam from the antennae will be everywhere except your kitchen. You can probably get great performance in your basement if you have one.
One thing that came out of my ill-fated access point stand project was that Ubiquiti changed their stance on vertical mounting of the access points and introduced their own range of horizontal wall mounts. So I’d be tempted to try a horizontal wall mount but ceiling mounted is absolutely best because although you don’t need a big surface around the access point for better performance it does help if you have some plane for the access point to work against.
Wall mount for compact UniFi Flagship WiFi access points.
eu.store.ui.com
I think the Lite mount will fit the UAP-AC-LR. If it’s a U6-LR then you need the other one (Pro).