Hey John. All 2x6 boards, plywood? Why not recommend a parquet floor. she said inexpensive!
I think she should keep her bedroom in the den and enclose the carport into a florida room with some plexiglass. Inexpensive, she would have a room to hang in, problem solved. You cannot inexpensively build a bedroom under a carport and I wouldnt't recommend it! However, you could make it an enclosed florida type room. Similar to an enclosed porch. Sort of a happy medium on her show string budget.