2013 Ram 2500 6.7- pull a Montana High Country 293RK?

Many people may consider that combo OK. However I don't think it is a very good match.
A Mega Cab with all the goodies has a very low payload rating.
You should have bought a 1 ton SRW version. Good Luck.
If this is a long term decision/situation. I would at least investigate the trade in value/possibilities or your current truck towards the correct truck. Good Luck

I'd tow that with my 12 Ram 2500 CTD. RAWR is 6000lbs My empty rear is 2950 with the B&W installed. That leaves me with 3150lb for the rear axle. I currently tow a 9000lb 5er with an 1800lb loaded pin. My dry pin is 1385lbs so I added 415lbs to it. Apples to apples I'd add 415lbs to the 293's dry pin of 2075 for a total of 2490lbs. That would leave me with 5440lbs total. I'm also RAWR limited at 6000lbs because of the 245/75/17 tires. Get an SLT and that goes up to 6200lbs. Put 18" tires on and the RAWR will go to 6800+lbs.

No it won't change the door sticker. For me that's not an issue. To others it may be and it's something the OP needs to address.

FWIW the 2013 2500 is an improved 2012 3500. Same exact rear springs as the 12 3500 along with the improvements made to the CTD and tranny.

Ironically a guy over on IRV2.net had a similar issue recently. He bought an F250 and a larger 5th. Both were suggested by the Ford dealer and the RV dealer. He then found out he was over his GVW by 7-800lbs. After he picked up the 5th and towed it quite a distance home, he came to the conclusion that it was fine. Most of the time he never noticed it was there. He also had air bags installed prior to towing.

Tow it...

I tow a 2013 Montana Highcountry 32xxRL with my 2012 RAM 2500 6.7 Cummins with no problem. It tows level without any modifications. The only difference in a RAM 2500 and a 3500 is the rear springs. All the running gear is the same and the Cummins paired up with a 6 speed auto trans will do just fine with a 3.73 rear end.

Well, what I see tells me that with your GVWR of the TV, you will be over that when you pack up the trailer.That truck will pull that trailer forever. The key word is pull. What will being overloaded do? Braking ability, springs,rear end, shocks??? I would seriously look at a lighter 5er for your truck. I pulled with a 3/4 ton for ten years and I was overloaded. Now have a dually and feel much more secure with it. It is what it is and you're the one who will have to deal with the situation.

It appears to me that the hitch weight alone is over your cargo capacity. Now, add passengers, driver, stuff you normally carry, fuel, and you will be way overweight. Adding airbags may help, but you need to consider what would happen to your warranty if something happened and you had to utilize the warranty. I would bet it would be voided. Not only that, but you didn't mention what the COMBINED GVWR of the truck is. You have to add the weight (outfitted with everything you can think of, including water, grey and black tanks full, because at some point that will happen, propane and any thing you carry in the truck or 5er) of the 5er to the weight (loaded) of the truck to determine what your GCVWR is and whether you exceed it. A good rule of thumb is 80% of your GCVWR is what you need to be safe. Whatever you do, don't forget that warranty, because it could be a killer.

You are going to be right at the max GVWR for your truck or slightly over and that's before you put anything in the trailer. I think in reality you will be over by 1000~1500# by the time your loaded.
If your comfortable with that (and many are) then go for it.
BTW, you don't pay sales tax on the trade in portion of the deal. So if the new truck is 50K and they give you 35 for your trade in, you'd pay sales tax on the 15K difference.