My Yukon's rear suspension sags when I hook up the boat - is that normal?

[valentinefurbank]

I've got a 2018 GMC Yukon that I use to tow a small fishing boat on weekends, nothing too heavy, maybe 2500kg total with the trailer. Lately I've noticed that when I hook the boat up, the rear end squats way more than it used to, almost an inch or two lower than I remember from last season. The car drives fine when empty, no bouncing or weird noises, but the sag makes the headlights point up at the sky and the steering feels lighter. I had the air suspension checked at a local garage and they said the compressor works and the bags aren't leaking, so maybe the shocks are just worn out and not providing enough support? I'm not really sure how the autoride system works on these trucks. A friend who tows a caravan recommended finding a specialist who can test the damping and the load leveling together instead of guessing. I found a company offering Efficient GMC Suspension Repair at Suspension Repair Dubai, and they claim they come to your home with diagnostic tools to check both the shocks and the air system. Has anyone here used a mobile service for a Yukon or Tahoe with autoride? I'm specifically wondering if they can tell me whether I need just shocks or if the air bags are also weak. Also curious if they carry heavy duty towing shocks or just standard replacements. Really want to tow safely without blinding everyone with my headlights. Any advice appreciated.