I run a similar setup. 1500 CC, short bed with a Forest River 27VRL travel trailer. My tongue weight is about 970#.
It came with a EZ-Lift WDH as well. What a *************. I spent a lot of time trying to dial it in, added a second sway friction bar, AirLift 1000 bags on the rear coils. It would still sway and porpoise no matter what. Sell that WDH, you'll thank me later.
I switched to a Equal-I-Zer 4 point WDH. Night and day. Very little sway, porpoising was mostly gone, but acceptable. After a few runs through a CAT scale to get it dialed in it towed great!
Now, I sold that WDH and bought a ProPride 3P. Sure, it cost me $2500. BUT, it's stupid easy to hook up. And there is ZERO sway. A dang 18 wheeler could probably side swipe the trailer and it still wouldn't sway.
Point being, get rid of that ************* WDH that came with the trailer and get a quality WDH. Equal-I-Zer, BlueOx SwayPro, Hensley, ProPride, Husky Centerline TS.
Anderson recently updated their WDH to handle more tongue weight. So, that might be an option as well. They are very helpful over the phone. At least when I called them a couple years ago they flat out told me to go with something else due to the tongue weight would cause their bushings to prematurely fail. Their newer ones are updated and more beefy. Some people on IRV2 are having good results with them. So, something else to consider.