I'm 6'4 so I'm worthless to you there but... I've met several short riders, most of them lowered the bike and regretted the handling effects. A girl I know rides with these cowboy boots type things with a real big pronounced heel which gives her several inches of lift while still allowing her to shift and brake easily, might give those a shot.
250's and older 500's seem real low to me, might give those a try. One thing I definatly suggest is going to a dealership with a large amount and variety of bikes and spend an hour sitting on them. I mean 5-10 minutes on each one your interested in. It's super easy to love a bike, sit on it and convince yourself it's perfect only to live with a mistake for a couple years. Put your feet on the pegs and see how it feels, sit up, crouch down, one foot down, both down, lean the bike slightly from side to side while on either legs, make sure it's a perfect fit. The reach to the handlebars should NOT be a difficult reach for you, you will get sick of riding really quick if it's a stretch to ride.
Random weirdness; some gnarly short harley guy I saw somewhere had these smallish looking wheels, quite a bit smaller than stock it seemed and it made the bike a lot lower. No idea how this effects handling or anything but maybe smaller wheels and tires are a way to lower the bike without effecting the handling as badly as dog bones?