I recognize that you are looking at the RT model because of its inherent cargo carrying capacity; however, from what I know about mine the only solid mounting option I see is to the passenger hand grips which are, IMO, a less than satisfactory idea because you are, to my slow brain, using only one point in the vertical plane to anchor the rack when two would be the minimum. Yes, you could mount a case transversely across the passenger seat area and that would give you two mounting positions but you're looking at 39-40" in case length before you would be, again IMO, having your cargo extending beyond the width of the saddlebags and you would be adding significantly to the barn door in the wind factor that will eat mileage. For that reason, I thing the better option Spyder-wise is an F3-S because it has a better mounting option for a vertical case. With the F3-S you are going to give up significant other cargo carrying capacity.