Rear Suspension Air Bags for my truck

If you only camp 6 times a year why bother.

We like to go to Marathon which is 900+ each way. I didn't know how it would be to pull that far with that kind of load.

I would want it to squat some. I sure wouldn't want it to ride like it was empty for 900 miles. :)

Not a big fan of bags, but in your case sounds like only for leveling.
Have you weighed your 5er loaded?? The 3,500# is the dry pin once loaded could be more. The Voltage 3970 shows a GVWR of 20,000, so I see the need for bags, you likely have a 4,000# pin.

Just make sure the bags you are looking at have an internal bumper, so you can ride with them with 0 pressure. One thing less to worry about in between camping trips.

Another option is Timbrens. I have them on my truck and really like them. Zero maintenance, they don't affect the empty ride at all and I really like the way the truck rides with the fifth wheel. The pin weight is enough to just settle the truck down onto the Timbrens. I probably have 3/4" of travel between the Timbrens and axle when unloaded. Just food for thought.

I'm a fan of air bags. Had them on my last three Super Duties; including the one I have now. I was actually able to get my Ford dealer to install the ones I have now. I love them. Air Lift 5000s is what I've used. 4 Wheel Parts carries them and if you prefer, they can also install.

As for the compressor, I recommend that as well. They're making them wireless nowadays so its easier to install because you don't have to run the gauge and stuff into the cab. They use a remote control.

op wrote:
My question is if this is a good plan to offset the heavier pin weight?

Is there any downside? It seems very common.

Many 4x4 trucks sit level and when weight is added the rear squats (has nothing to do with being overloaded).

Assuming your trailers pin is not aft of your trucks rear axle air bags is a good plan.

Which ever brand system you choose do the 1-800 number and get their input on your combo's particular requirements.

Just mounted Firestones on my smaller rig. Used to get about 5-6" of sag at the rear bumper. Never an issue "bottoming out", even on rough roads before, but I didn't like the "uphill" feel of the truck, nor having to use the jacks to take up that sag before I could unhitch. Currently have only pumped them up to 30lbs when on hitch, and only have done a very short drive. Sag is now 2". Handling was fine. Off hitch, have been running the 30lbs for a couple of weeks. Not a lot of difference - a bit stiffer in the rear, but nothing my wife or anyone else has noticed. Using a bike pump, and while it does take a bit, it only takes about three times the number of strokes that my high pressure bike tires take. For the few trips a year, I can justify it as exercise. I'll play with pressure, but it may not need much more.
I didn't know about air-rides (I think that is the brand with the internal bumper) before I bought the Firestones. I might have considered. But so far, I have no issue with the Firestones. BTW - buy the separate air line Tee made for them too. That way you can fill both at once, rather than having two fill valves. Air-Ride Tees are cheaper than Firestone and work on the 1/4" air lines too.
And...I originally used the "no drill" bracket for the fill valves, that straps to the vehicles hitch. Location made it hard to attach the pump to the valves. I drilled a hole next to the license plate for the single valve, and it works well. I've seen examples where the valve replaces one of the plate screws, making it almost un-noticeable. But on mine, I would have had problems with getting the pump onto the valve.
The big test - leaving next week for a 1 month, 4.5K trip, so that will tell the tale!

I Have a very similar situation and can say without a doubt I LOVE the airbags. I have a 2013 DRW F-350 I pull a 2015 Voltage 3818, before the airbags I had the same Issue you have. It's not horrible or overloaded just not perfect, I installed Bags and a wireless system and the combo is perfect. I Typically pull with 80 #'s of air in my bags and 80#'s of air in my Trailair and the ride is amazing. Before the bags I felt every chuck and small bump in the road, now I only get feedback from really big road bumps. Take if from someone who has had several sets on various trucks, buy the wireless system. I know it's not a big deal to add air while hooking up or when auto retract is working etc. However it's great to back up to the pin, drop the front legs and go select how much air you want in the system then simply walk away and continue your routine. I had the manual fill style on my previous vehicles and will never go back, you will find if you use your truck for anything else you will use the bags and won't always have air available.

Install is very straight forward and easy, I was going to pay Ford to do mine but I enjoy tinkering. The biggest Issue you will have is mounting the compressor and valves, there is next to 0 open space under the hoods of these new vehicles. The compressor does not have to be mounted under the hood but I like it to stay warm and dry. Lucky for me I have an aftermarket air intake and was able to work with the space that the factory intake takes up.