Let's say I have VI RAC, carrying a Courier Droid ("At the start of the "Place Forces" step, you may choose to treat your pilot skill value as "0" or "8" until the end of the step"). What are my options for PS during placement?
0, 8, or 10 - The "may" in Courier Droid applies to using it at all. You don't have to use it, so instead of the 0 or 8 it allows, you can use your own PS. (I believe this is the intent and the strongest interpretation.)
0 or 8 only - The "may" refers to having a choice between 0 or 8, but because you're equipping the Courier Droid, you're using it, so you must use one of those: 0 or 8.
In plain English, if someone says, "For lunch, you may choose PB&J or sloppy joes," this can be interpreted in either fashion above.