My thoughts are,... if you want it to work.. you will find out a way to make it work! I think it's a fabulous idea,personally! I would be tempted to keep your actual sewing notions with your sewing machine in your new space, after a few trips you will begin to know what you need right beside you. You could set up a 'mini' ironing space if you don't want an ironing board right beside you..some folks re purpose a tv tray for a mini ironing area. Perhaps by the time you get all your notions etc right by your new sewing area, the only thing you would have to do is use your upstairs space for storage and cutting.... JMHO
Good luck! I think it would work!