A plan might enable her to agree, in principle, because she would know I was serious, so that's a really good idea, but I have given up in trying to help her see with my vision. I do have detailed plans for lashing the corners, properly, as opposed to the cross brace's lashing method, how to support the headers (and how big they should be) above the windows and doors, size of the rafter pieces, overhang of the roof, along with a rough idea of how much earth I will have to move. None of that is very impressive, though. Maybe I should have her pick out the curtains, first and I can build around them.
Why not add on, another room, to her play fort?