Well you are going to be over your GVWR, so I can only tell you what I do, but can't recommend it as that is your choice.
We tow a 2005 Keystone Copper Canyon 293 FWSLS with our 2001 Ram 2500.
5er
Dry 9,860#
GVWR 12,360#
Wet 11,000# (weight I tow at most of the time).
Ram 2500
GAWR Front 5,200#
GAWR Rear 6,084#
GVWR 8,800#
Last couple times we have hit the scales truck scales at 10,000#, 5er about 9,100# on the axles total GCVW 19,100#+
I worry less about GVWR than axle and tire ratings!!!!
I have 600#+ to spare on each axle. My 265/75-16E tires carry a 3,415# rating each. So I have 1,284# to spare of axle capacity and 3,660# of tire capacity.
I do a lot of towing into the Oregon Coast Range, I don't hold up traffic can pull at speed, and feel 100% safe driving the narrow two lane state highways to the coast. this with a 5.9 with 277,000 miles and less than 285HP.
The choice is yours, keep in mind if you have 17" tires, the 265/70-17E only have a 3,195# capacity each.
That and you will be over your GVWR.
That is this rig, without bags or Timbirn's
Running on roads like this at 55 to 60 mph.
