FWIW, I've found more and more dealers will not sell a trailer to anyone who has a tow vehicle not rated for the max GVW of the trailer.. Ergo, if your truck is rated for 17,100 but the GVW of the trailer is 19K#, you're either going to be refused or, if they do sell you the trailer, you can get yourself in biggie trouble with the law IF you ever have any kind of accident while towing..
JMHO, but I'd urge you to stay within limits of the vehicle when you search for a toy hauler..
I just traded my '11 F-350 for a newly ordered '16 F-350 PSD DRW with the max tow package. It's rated by the factory to tow up to 26,500#. The hitch I switched over from the other truck is a Reese Elite rated at 25K#. Part of the reason for the new truck is that the toy hauler I want to get soon is a DRV Fullhouse that has a GVW of up to 24K#. My other truck was rated to pull 22.5K# and that wasn't gonna do it..
Rule of thumb - you can NEVER have too much truck, but you sure can have too little; and I see examples of that in many, many campgrounds.. Personally, I'd never take that chance..
FWIW.
2012 Keystone Raptor 365LEV
2011 F350 DRW, CC, LB, PDS w/AT, Lariat pkg w/moonroof, tow/camper pakg and Ford 5th wheel 25K Reese Signature hitch option.
2007 HD Super Glide, bright red
2009 HD Ultra Classic red/gold