I don't think they warranty holes at all so your on your own when you drill, other than the stock holes for the overflow. Unless it is the manufacturer that is doing the drilling.
That is one reason why I'd go with 3/4"BH outlets, about 4 of them & One 2" for the 1 1/2" suction. Now on the bottom you can do a 2" for each overflow & call it good, you can return your sump over the top, actually you can even return the CL over the top but I'd place at least two 3/4" down low to cover the bottom areas. So you have there several choices for drilling holes! I'd come up with a few sketches & post them & really think about how you want to do this & have it planned before you do any holes!