I don't think a Viper plant tour is in the works for this year. IIRC, they have moved production to another plant and the old Viper/Prowler plant (that we toured at SDAC-7) is closed now.
We are looking into other "interesting" items, but they most likely will be announced only at the event, not before. That way if they don't happen it won't be a let down for everyone.
Barry