I would just tow with it. My guess is you'll find that it's fine as-is. Lowering the CG doesn't help towing much, but it has a big effect if you get the trailer, um... crooked.
If you do a panic swerve and the trailer gets up on one wheel, then a 1-ton dually will be less affected than a Caravan. So yes, lower CG is a safety item, but not from the standpoint of nice comfy towing. It's a safety item in terms of panic situations. Lowering the CG prevents those panic situations, but doesn't do much for how it tows in a straight line.
IIRC, your rear springs are coils, yes? I suggest against the urethane airbags that fit inside the springs. They might work on pristine, new springs that are 8" away from any exhaust, but all it takes is one crusty piece of rust. I put helper airbags in my Impala SS springs to tow a boat. On its maiden voyage to Lowes 5 miles away, the right side melted through from the aftermarket exhaust and the left side rubbed a hole through from crusty springs.
A viable solution for LIGHT assistance is to get air shocks. If you do that, keep in mind you'll be transferring some of the weight from the spring perches (which are designed to take a ton of weight) to the shock mounts (which are not designed for too much extra weight). Use them sparingly. The other downside to air shocks is that they require a minimum psi or they become damaged. When you're not towing, you can't just dump the air and ignore them. They require constant verification that they have some pressure in them. One good bump that loosens the cheap air lines and 50 miles later you have normal shocks.
If you find you're having trouble with tongue weight on a factory suspension, the first thing I would go to is stiffer springs. You can source springs with a higher rate (but shorter unsprung weight if you don't want to change ride height). The upside is that's the "right" modification. The downside is that daily driving will be less cushy.
Suggestion... if you need to stiffen it up, start by getting the rubber spacers for between the coils. Not a donut spacer under the spring, but an X-spacer that goes in between coils. This won't affect ride height, but it takes one coil out of active duty, thereby increasing the effective rate of the spring by a completely unpredictable amount. I don't consider this a viable permanent solution as they can fall out causing an unpredictable change in dynamics, but it is a $10 and 10-minute way to simulate what a spring change might feel like before tearing apart a suspension.