Thanks everyone for the great suggestions! I have a great tank bag (Oxford First Time Luggage) which I carry everywhere with me as it's great for the daily commute to fit lunch, and any small items on a day trip. The luggage is for longer trips which may require some more items.
The Twisted Throttle site basically has only waterproof bags which attached to the passenger seat, at which point I even considered taking a standard small duffel bag I have and attaching it with the cargo net! Although not sure how safe/secure that would be! LoL