Rather than use Skitarii or Tech-Guard as the infantry support for my Epic Knights, I'm going to use the robots of the Legio Cybernetica. It's not clear whether robots (or indeed, Knights) are still around in M41, but that's not a big problem, as we know they both were during the Great Crusade and Horus Heresy, so this army could very easily be a pre-Heresy or Heresy-era army.
Here's a picture of the assembled maniples just before they went into Dettol to be stripped. In OpenEpic they represent about 2,000 points, which should be enough to provide the Knights with a screen of ground pounders.
You can see a mix of all the different robot types (Crusader, Castellan, Cataphract, Conqueror and Colossus) in both metal and plastic.