He does NOT need sleep more - you do!
You are heavily pregnant. You need to be thinking about staying rested and as healthy as possible in preparation for birth.
Mat leave? No, you aren't though are you? 'Mat leave' - as in having the house to yourself all day every day so that you can relax, get back to sleep if you need to? No. You're living in someone else's house so are up at the crack of dawn because of their noise, you can't sleep in the day and you have to be on the ball because you're managing a building project?
Have a think about this - you are already subconsciously simply prioritising your DH over yourself, just BECAUSE.
The fact is that both of you have long exhausting days with lots to do.
You both need sleep.
However, your physical state means that you can't do a camp bed at the moment, on top of the fact that late pregnancy is hard in terms of sleeping/being comfortable anyway.
He doesn't have these issues and would get perfectly ok sleep on a camp bed, just as you would if you weren't pregnant.
Your 'D'H actually watched his heavily pregnant wife try to sleep on a camp bed mattress and didn't offer to take it instead?
What an absolute prince!