Outwell Nevada M Kid's room

[MS1713]

Hello all!
I'm on the hunt for a kid's room for the Outwell Nevada M and thought I would pick your collective minds.
I bought one for the Minnesota 4 as the measurements of height/width/length were all the same but I think the gradient of the walls/ceiling was different as it was just a bit too 'off' to fit properly. I managed to find a new one on an Austrian site but it's about £70. I love my girl but I'm buggered if I'm paying that!
Any ideas, people?
Thanks!