I frequently tow a Coleman Cheyenne TT. I typically experience two different styles of trip every year. The long haul paved "family" trip (read: National Park, 100 ft of gravel if I'm lucky) and the off-road into the middle of nowhere fishing trips with "the boys"(read: forestry trunk roads and un-maintained service roads that lead to un-maintained camp sites.
Here is my experience with my tent trailer.
Trailer is 2990 lbs without water/beer/bikes with a 375 lb tongue weight. 2 x 31 series deep cycle batteries and 2 x 30 lb propane tanks bump up the tongue weight..
When its loaded with food/beer/bicycles tongue weight drops to 330ish and the overall weight goes up to 3200 lbs (TT has a 3500 lbs Dexter axle). The before mentioned additions go behind the trailer axle.
With me and the "family" and all the crap we bring... I am adding about 4000 lbs of load to the drivetrain/brakes (in cab+trailer). I have towed this setup over the Rockies from Edmonton to the west coast and back every year for the last 10 years, 2500km round trip. I have done 7 trips with this setup and my 2012 Trail so far. The T4R does just fine! Fully loaded I have to keep the transmission in 4S on the highway or ScanGauge trans-temp gets dicey. I have no issues going up or down 8% grade roads as long as you don't try to maintain 70 mph! YES, I have been into 2nd gear a few times but hey, enjoy the scenery. I think that only happens for like 5 minutes on my typical west coast trip. Then there are a few times where I have to keep it in 3rd but I can maintain speed, again 5 minutes tops. Just have to buzz the motor, no issues! The brakes in these 5 gen's are pretty stout. You just have to LEAN on them, but they work well! BTW-Camper has electric trailer brakes too.
I have added an Anti Sway brake. Works PERFECT for the camper!!!! NO oscillations on the highway at all! Trailer tracks nice and straight and behaves on radical lane changes like accident/deer/moose avoidance maneuvers. DO THIS MOD!
I also have the Firestone Air Rite airbag system installed. The system definitely will help with leveling the T4R and improving the ride for the occupants but...I have had issues with them...
First set, I got a bad one and it split at the molding seam. (defect) Firestone sent me a replacement, but I had to buy another set of air bags while on that trip to get me home. (Yes, you can change an airbag with the factory jack and a chopping block in the middle of know where. Lubricate well with a beer

).
I have had two individual failures since then. The bags on different sides, split where the bag contacts the spring perch on the axle. Both failures have happen during the winter season where the outside temps dip down to -30 deg C, NOT while towing. I think the vinyl bag gets too hard and breaks when it hits the edge of the spring perch on the axle. Postmortem shows this contact area and break.
So every spring I put go through the dance of replacing a bag and sending back to Firestone under warranty.
After the second bag failed I installed a set of Timbren rubber helper springs. They will keep the T4R level but you will get a VERY bounce ride! I got the "Is it always this bouncy?" question from my wife the first time I tried the Timbren's. I have removed them have stored them in the camper as a "get out of jail card" if a bags fails while I am in the middle of nowhere, as I can install them in about 5 minutes if need be.
Last week I replaced the airbag on the other side from last year, same failure. So I modified the spring perch. I took the two old cracked bags and cut their tops off. Then flipped them over and created a pocket for the installed bags to rest in, instead of just on the perch. A kind of saddle to distribute the contact area a bit. The pockets are held in place with some RTV and are currently holding well. We'll see what happens this year.
I like the air bag system for controlling the ride height, just no too impressed with the reliability. I will try this last attempt and if it does not survive the winter I'm done with the Firestone system!
I few days ago I also purchased a weight distribution hitch and will install it this weekend. I hope that this should keep my comfy ride/height and mitigate the reliance on the Firestone system to keep the T4R level. I will update on the results of the WDH after the first trip in a few weeks.
I hope you take away some valid info from this write-up.
The following picture was taken just before the first test drive and after I did an axle over/under conversion to the TT. I also added 205/75R14 trailer tires as well. This mod gave me 6.5 inches of additional ground clearance on my TT. The Firestone bags have 8 psi in them and everything is level and the test drive went perfect!