Maybe you could just ask your husband to build a one story house with all the normal rooms....LR, kitchen, bedrooms baths etc and to add a one room second floor to fit the footprint of the main floor for your sewing room. Then you would really have a great size room depending on how much square footage the main house has. Oh and be sure to include an elevator to make it easier to access. A large elevator! and a bathroom of course.
You did say dream sewing room!! That would be mine.