Lets get real and put the numbers out there....
That Montana 3610RL has a GVWR of 16,790#
That Bighorn 3169 Elite has a GVWR of 15,500#
I don't care what magical mfg. published tow numbers are......both of those 5vrs are DUALLY not SRWs.
If you are really set on an SRW then get a lighter 5vr.
No fun towing when overloaded....that means less frequent trips...that ends up using RV less...that ends up with it sitting around unused and costing big $$$
I have an SRW......5vr GVWR is 14,375#.
It is a great towing set up BUT any heavier of a 5vr.......it's DUALLY time. Plain and simple.
An SRW will run out of actual payload capacity, GVWR, RAWR, Rear tire max load ratings long before that mfg. max tow rating is reached.
That is for real.