I don't know about the XI5 but I had a Terrova and read a lot about placement issues. Get some chalk and outline it. Open and closed and consider how the boat slides off the trailer. Measure and remeasure and then drill holes. There's still going to be doubt in your mind about drilling even after you do all this. If you take your time, you'll find the best spot for you. Mine never had any of the common issues loading or unloading.
The other option is to see if they have a sliding plate that you can mount it to.