I drilled some holes into my router base and attached the base to the router
That voids the DeWalt warranty? As long as your problem (the one that falls
under the warranty) was not caused by the holes in the base, I can't see how
they can contest it. At worst, you would have to buy a new base before
submitting your warranty claim.
However, I looked at the "router table" that came with the craftsman saw
when I was in the TS market a couple months ago, and decided the table
wasn't worth using. Think about that before you drill your router base.