You could get a kilted skirt made to the length you want or get a mans tank, makes no nevermind to me. When to wear it, any time you want to look nice, not just major dress up occassions. Wear it with a nice blouse or shirt and there are some very nice ladies jackets that would work nicely. Ladies suit type jackets are cut much shorter than mens jackets so no mods should be needed. The Stillwater alternative is there as has been mentioned in case you really aren't sure about spending the money on a custom tank. Whatever you decide, do it and revel in it.