In my experience, several things can help mitigate sway.
1) Is your trailer level?
2) Is your trailer properly loaded (proper tongue weight)?
3) What is the load rating of your TT tires?
4) What PSI are you running them at?
5) Are your TT tires cheap (MIC)?
6) What is the load rating of your Titan's tires?
7) What PSI are you running them at?
8) Are your Titan tires cheap?
I'd make sure to address numbers 1 & 2 first, as they are free. Numbers 4 & 7 are relatively cheap as well.
The TT tires should be maxed out on inflation, according to the numbers on the sidewall of the tires. If you're still running the OEM p-metric tires on your Titan, I'd strongly consider replacing them with a good quality Goodyear, Michelin, etc., that has an load rating of E. I would tow with the tires inflated up above 65psi. Its the air pressure that carries the weight, not the sidewall of the tire. Now, a stronger/higher quality sidewall/tire will dramatically improve ride comfort/confidence. While on the topic of tires, if you're still running the cheap Chinese ST tires on your TT, you need to dump them. You want to find a Goodyear/Michelin/etc LT tire that's the lease aggressive tread pattern that you can find, with the highest load rating. At minimum a "D". For instance, the Goodyear Wrangler HT is a great option. Buy five. You might have to step up one wheel size to find a tire that will work. If you're running a 205/75-14 load range C, I'd look to see if like a 215/75-15 load range D (LRD) would fit. I'd again, always run the max PSI that the TT tires allow for. Check it frequently.
Sway-mitigating hitch. As mentioned by others, hitches like the Reese Dual-Cam hitch is fantastic at attenuating sway. But it has to be set up properly for it to be effective. That includes having a level, and properly loaded trailer. If you're unable to get the truck and trailer level, then yes, I'd absolutely add a pair of airbags. Make absolutely certain that they are plumbed exclusive of each other. They can't be Tee'd together.
You should really choose the tires carefully. You can't cheap out. You'll just be throwing money away.
If you question my experience/authority on the issue, take a look at my sig pic. I've gone through the same evolution of problems/solutions as you. I've towed/hauled the below setup all over WA, OR, ID, UT, & CO. It's rare that I drive with more than a thumb & forefinger on the wheel.
My TT is 32' long overall. The ATVs weigh in at 550#ea, plus the rack & gear.
**Note: the pic was before I added FS RideRite bags to the rear.