4500 lbs is way too much for a single axle trailer, unless it's incredibly heavy duty.
Lately, I've spent a few hundred miles in front of a 5,000 pound dual axle boat trailer with surge brakes, and it's been a pleasure. The V6 is taxed on long uphill grades, but otherwise, it does really well. Nice and stable, easy stops. The various (lighter) single axle trailers I've pulled without brakes have been more work to tow. Not as stable, harder to stop.
The other nice thing: Bridgestone Duellers have saved me from having to trade for a 4 wheel drive. I'm getting up some steep, muddy, sandy, wet ramps without even breakign the wheels loose.
The ST can be worked pretty hard and not complain about it.