We were thinking about letting my DD be a nurse or dr this Halloween. Buy a set of scrubs, a stethscope and make a orintable name tag. Even if you don't sew, it's easy to buy hemming tape, and just cut the pants to lentght and iron on the hemming tape. You could do a cowgirl, a witch, a rock star (short skirt, fishnets, boots, tank w/a ripped up t shirt and colored hair spray), a farmer (overalls, flannel shirt, John Deere cap) a Mom (jeans, a "spitup" stainrd tshirt, frazzeled hair, with a burp cloth and baby conveniently attached to the shoulder, a diaper bag) a hippie (search out the consignment store or thrift store for bellbottoms, headband, peasant shirt). Those are just a few I can think of.
We were having the same issue with my 8 year old. She's also 5 foot, waers adult clothes, and everything was too adult. Well, last night we found my 4 yr old DD a bride costume with a veil. I suggested my 8 yr old be a bridesmaid, and she loved the idea! So we are going to find the most outrageous bridesmaids dress we can at the consignment store, a pait of dyeable shoes and voila a bridesmaid she will be.