Well, there ARE pre-drilled holes. Those are meant for aligning the ‘bunks’ that are provided with the kit. If you intend to mount to a trailer that is narrower than the camper itself, then you ‘might’ need to use them. Essentially, the ‘bunks’ are longitudinal rails, made out of 18mm plywood, that are used to elevate the shell about 3″ above the mount point (in most cases, that’s the wheel wells). My impression is that they were meant for mounting to a smaller ‘harbor freight’ style trailer. For most other trailers, you’ll be doing a ‘drill-fill-drill’ where it makes the most sense for your case. Hope this helps.