Damn, 11.5" to fit 13.5" into....it does sound tight.
The depth of the Warn and the top profile, mean that the winch's front would have to be about 6" forward of the bar...the winch is about 6" deep, ...I don't think the bumper's that deep though at the winch plate?
Do you have the bumper, and are considering the winch?
If so, just go to a local 4wd shop that sells the powerplant, and ask to see if it woud fit...maybe it just works once you have it in your hands?
I looked at one a few weeks a go in a shop though...and that mo fo is HUGE!