Recommendations for drilling a lot of small holes in various plastics (ABS/PVC/Acryl)
The scope of your project requires an equally large scope of preparation. Swap out the ladder for a scaffold system. Replace the hand drill with, at a minimum, a drill jig to keep alignment while you drill. Use drill bits designed for drilling plastic to prevent cracking. Your emphasis on avoiding splintering/cracking increases the importance of proper drill bits. Using such a small diameter drill bit also increases the chance of snapping a bit in the hole. With a combination of scaffolds, a drill jig and proper bits, you may be able to accomplish your goal.



You suggest that the holes need not be perfectly straight, but a jig will enable you to drill in a safe manner to avoid snapping a bit.

A quote from a plastics web site:


  Plexiglass, Lexan, Plastic Drill Bits These are the bits you need for drilling Plexiglass, Lexan polycarbonate, PETG, and other clear
  plastics. The special tip design carves through the plastic (not for
  use with wood or metal).
  
  It takes a special drill bit to properly drill through Plexiglas,
  Lucite, Acrylite, or Perspex acrylic sheet. Ideal for Lexan, Tuffak or
  Makrolon polycarbonate sheet. Special 60 degree angle. Not recommended
  for wood or metal.
  
  These are specially ground flukes with a 90° point for drilling holes
  in acrylic plastics including, Plexiglas®, Lucite® and Acrylite®
  materials. Metal drill bits will not work as they are made to bite
  into the metal as they are pushed into it. If they are used on
  acrylics they will chip and cause other damage to the plastic.
  
  When drilling holes for screws, you must make the hole larger than the
  screw itself to allow for expansion and contraction of the material.
  If not you will cause stress cracks at the hole and they will spread!
  Always have a backer board behind the plastic sheet - most problems
  happen when you punch through the back side. The design of these bits
  helps prevent that!


Bits for cutting plastic have a shallower angle to the tip as well as less aggressive cutting edges. The one in the photo below shows it is nearly a scraping edge rather than a cutting edge: