I am a horse owner and pull these type of trailers regularly. I would say that a good brake controller, airbags and a set of gauges to monitor the vitals are a start. When you are towing the trailer are you having any issues?
The airbags while help control the trailer especially when the horses start moving around. If you haven't towed horses, they can easily push the rig into the next lane when they start rocking. You gain almost a sixth sense of where the horses are standing during the haul.
Also, I would say that anything to free up the breathing of the motor like your intake and exhaust will help the motor run cooler and stronger.
Sold - '03 ECSB Silverado 2500HD - LB7
'06 Silverado CCLB Dually - LBZ
EFILive Tuned by Mr. Willis