We are in the same boat as we have the '15 version F350. Based on current 5er and prospective new 3560SS, I'm figuring on being over on truck's GVW of 11,500 by anywhere's from 500 to 2,000 lbs and combo by same weight. Here is how/why I think so.
Current coach has a pin (fully loaded) of 2180. 5er itself fully loaded 13,160( just the 5er, no truck attached) (and still have room for 600 more lbs). 5er empty is 1800 pin and 10,800. With 5er hooked and loaded, steer axle is 4920( 4860 w/o 5er, 6,000 capacity). Drive axle is 5860 (3680 w/0, 7,000 capacity).
BC 3560SS should add more weight to steer axle, but still be under or at very least over by less than 500 lbs. For arguments sake, say 5500 on steer. Drive axle w/ say a pin of 3400 (loaded) should put me around 7100. So adding 5500 + 7100= 12,600. Over on truck, but IMO tolerable. If the BC has a max GVW of 16,000 and less cargo of 2500, then empty weight "should" be around 13,500. So you load it up w/ stuff that equals 2500 and you're back up to 16000.
If my math is right so far, based on my trucks empty weight and BH gross weight, new combo weight again "should" be 24500-25000. So over on combo by 2000 (23000). Again, IMO tolerable. I'm sure the truck mfr's tested their trucks w/ far more weight knowing folks like us will push it, so I wouldn't be too concerned here. IF the number's were like 4000-6000, then YES I would throw up the red flag.
Will try a side by side comparo:
Truck alone Current 5er (loaded) Current 5er Empty BC Empty BC Loaded (estimated)
Steer axle: 4860 (6000 cap) 4920 5500
Drive axle: 3680 (7000 cap) 5860 7080
Trailer axle: 10920 12400
Gross: 8540 (11500 cap) 21700 10800 13420 24900
Pin: 2180 1800 2888 3400
CCC: 3000 2500
Please note that the weights for current 5er and truck are CAT Scale weights from Aug 2015 on week long trip to NC.
Sorry about the compars being so close. Don't know why it happened as I had them spaced out nicely till I hit submit.