Road Armour Stealth bumper - parking sensor install

Hi Everyone!
I have searched the forums and google and have come to the conclusion that I should be able to install my front parking sensors into the Road Armour Stealth bumper (about 4mm thick steel), however I thought I'd just double check by asking! The bar came with my truck (I'm in Australia so not much choice anyway - these retail at $5500 here) so I'd like to use it if possible. Pretty much no chance of being able to sell it - probably only a dozen of these in my state. Before going to the trouble of working out what size hole I need and drilling it out (I have access to a full engineering shop so shouldn't be an issue) I'd like to know if I'm wasting my time for some reason I haven't thought of! Also, if anyone has done this, what size hole did you drill?
Thanks guys - I did search first but if I somehow missed something sorry!
Cheers
Tristan