I have a race car. The purpose of drilled and slotted rotors is to allow venting of gasses that build up from brake pads on a race car. ( if there are any gasses there ) Supposedly, the gasses may inhibit the braking process. However, with a trailer, no one is going to build up gasses that would inhibit braking. Drilled and slotted rotors are mostly for show anyway. Don't waste your money. The only type of rotor that will help is one that has been cryo treated and that rotor would go on your tow vehicle. They will not help the braking process but will help with wear. To help with braking, the pad composition is way way more important that rotors in comparison.
The rotors from Titan or Kodiak are vented anyway. There is a gap in the rotor walls that allows air to pass. The air passes from the center of the rotor to the outside. This is how rotors are cooled. ( in addition to the outside surface ) In some racing rotors, the vane between these walls is curved to aid in this air moving process. In my car, I have a duct that blows air on the center of the rotor to aid in the cooling process. My rotors are not drilled or slotted but I do have special pads and I have no braking issues.