I'm not familiar with that battery, or your trailer, but a few thoughts:
1. Determine how many of what size batteries you can fit in your battery compartment. With this, consider your needs based on the type of camping you will mostly do (i.e. boondocking vs camping with available shore power).
2. Purchase flood cell marine/rv batteries from Walmart, Costco, Interstate, etc. They work well, are relatively inexpensive, and are easy to replace if they are prematurely "killed". True "deep cycle" batteries are better, but "deep cycle/starting" batteries will also work while you are figuring out your trailer.
3. By the time the marine/rv batteries are worn out, you will have a much better idea what you need and can upgrade if necessary.
As a side note, my original flood cell group 24 Interstates are over three years old, and still work great. I will, however, be replacing them with something different, (like two 6 volts) for more capacity. But I would not have known this when I bought the trailer.
Good luck and enjoy your trailer!