Welcome to the forum and irv2.
In
QT's # 3 there is a section on remodeling of coach's your dog house is most likely fiberglass and rug will have to be formed around the curves as you glue it, should not have problem with the floor layout you only have many staples to remove from old rug.
Here is a
Brochure and
Owners Guide for you.
Below in my signature are many links for your Newmar.
Enjoy the forums and safe travels.