I think you may be pushing it, depending on how much gear and people weight you add. You can do it, don't get me wrong, but how safe? I made 3 trips with my 02 that has > 130k miles on it. I have 5 kids and lots of 'stuff' and I did it, but struggled a few times. I have now been out with our new 3/4 and it's night and day. I hit some of the same route that we were out with the old truck and this one handled it with aplomb. Sometimes it stayed in 4th when the other would have been in 3rd; other times it used the same gear but just seamed to handle it much easier and with plenty of power to spare.
Stopping though - I'm not sure I notice much difference. I've always tried to leave plenty of space and slowed down early. I had to stand on the brakes once, and I had no problems taking off some speed and keeping it straight without fear of hitting anything! The old truck was rated for 7400. That didn't leave me a lot of head room for anything much!
My 29SS has a sticker that rated me dry at > 6200; my truck is rated at 9300 (4:10 + Dana 60 axle) so I'm hoping to have options for kayaks and/or bikes without any issues!
'12 ST29SS Reserve
'16 GMC Yukon XL, HD Tow Pkg. 3.42
1 wife, 5 kids, 1 rescue lab-mix