If you can't get Max and Speckles out of the house, then I would think crates are your best option. At least that way they can have everything they need with them, they will be safe from being stuck in the walls, and hopefully feel they are safe from the intruders. Sorry, I really can't think of any better solution.

A couple of weeks ago we had Daisy trapped in the house, because she was getting her eye ointment. One of the days she was in, the gas board were here replacing the boiler and doing some work to the radiators, so there was lots of banging and pipe noises coming from the walls. I was worried about Daisy, thinking that she would be really scared. Se didn't much like the banging, but she didn't act particularly scared and she was absolutely fine as soon as it stopped.

I hope Max and Speckles are more comfortable than you expect too.