Have a look at a Darche Ridgedome Tourer 1100. BCF has them on a good special at times.
Roomy as.
A thing to look at is how high the actual dome part is. Some are just of you, others are very generous.
As mentioned, put it on a stretcher. Warmer, more comfy for sleep, and way easier to get in and out of.
And if you can, do what Paceman suggests.
I bought one for my son's 18th, it won out against everything else in a similar style. Better than a Darche Dirty Dee and Dusk to Dawn.