There are several popular hitch systems available: Equal-i-zer and Reese are the ones most use with a combination such as yours. Reese makes one that looks a lot like the Equalizer (I can only type those dashes once in a while) and one with chains. I have the Equalizer. The Hensley and ProPride and two other brands. The ProPride costs less than the Hensley and appears to be an improvement on it. Contact Sean Woodruff, a Forum member, for more info on the ProPride. Both of those cost a lot more than the Equalizer and Reese and may not be necessary for a 25' Excella.
Understanding the dynamics of these systems can be a challenge and there are threads about how to adjust them. People get very emotional about their hitches too.
But it's important to understand how it works and how to adjust it for proper weight distribution, sway control and getting the trailer level. The instructions for the Equalizer do not tell you enough and if you get that brand, check out this thread, especially posts 13 and 14, for more information how it works:
You can also call the company and talk with them in depth to make sure you're doing it right.
Many dealers either do not how to install what they sell or don't take the time to do it right, so doing it yourself is a good idea. Until you figure it out, you won't know if it's done right, and until you do the whole thing yourself, you won't understand how it works. Setting it up takes a long time and much experimentation. It's tedious and daunting, but necessary. Good luck.