I tow an 8289ws with a 6.5' bed...no slider and the Revolution is locked. I can't say that I can do 90°, but I can maneuver the trailer anywhere I wish. Frankly, I find all the marketing hype about turning a 5th wheel 90° laughable. You don't see the TT crowd worried about turning 90°. And our 5th wheels are naturally more maneuverable anyway (pivot point further forward).
Remember...SB trucks w/5th wheels don't dent cabs....DRIVERS of SB trucks w/5th wheels dent cabs.
'04 GMC Sierra 2500HD, CCSB, D/A, MaxBrake, B&W Companion, Retrax Pro, AR Power Steps
2013 Rockwood 8289WS w/Diamond pkg
1969 Camaro RS/SS Convertible
Dad's old 1968 Empi Imp (recently recovered from under 21 years worth of boxes/dust)