X-pen/crate recommendations

To keep it simple Bandit needs his own area where he can just chill without the kids bugging him. I can just tell Briggs puts him on edge sometimes and as he is getting older and Briggs is getting larger I can tell Briggs' crazy behavior frightens him. If he is asleep and Briggs wakes him up he looks really scared and stiff. I can't 100% supervise their interactions all the time as stuff needs to get done. So obviously for everyone's safety and comfort I would like to start putting Bandit away for part of the day.

Suggestions on what to do? A crate isn't something i really want to stick him in as small areas DO bug him. Is there anyway I can mak an Xpen less moveable? Because Briggs will just push it around everywhere if thats the case.

Our x-pen came with little clamps to put on the top (or bottom?) to help keep it in the square shape.

What about a baby gate in a doorway?

I dont want the kids or him knocking it over.

The baby gate? Could you screw it into the wall? Mind is, and I could even sit on it and it isn't going anywhere.

Derp that could totally work