I have for sale a BICE Walkyguard dog guard, I purchased this from the roof box company. It does NOT have a top bar, but I used this guard in my Peugeot 3008 without any issues.
This guard requires the rear head rests to be extendable in order for the clamps to attach. I've added a picture for reference, the guard is extendable in width which makes it fairly universal.
This is a brilliantly made product, and because it's adjustable it's easily moved to another car if needs be. It can be mounted in a hatchback or MPV.