I think you could use the stock SF rear end - use a bit of imagination as to the connection of the 1098 pipes to the SF headers - it can't be that hard OR expensive - a few cuts/welds by en experienced guy should do it. The Motowheels undertail exhaust I put on my bike is attached by two of the four bolts (the front 2) that originally supported the hanging tail section - making a bracket would be easy. I'd like to see somebody try this because it seems at first glance to be not that difficult.
I already have undertail exhaust so it's not likely I'll try it. That said, it's all about air movement and leaving spaces for the air to escape freely. Heat guards can also be used. I still believe that irt can be done effectively.