I'm not sure I could advise on how it would best be handled, but absolutely, it would strengthen the bill to have a reference to UNDRIP in the bill. Whether it's in the preamble or written into the actual content of the bill I can't really speak to, but certainly I would support such an amendment.
Just to comment on the issue around the consultation with indigenous people too, most of my experiences have been working with the Aamjiwnaang First Nation. Certainly they call their situation environmental racism, so it is hard to imagine that they would not support a bill that is targeted at addressing environmental racism. They don't shy away from using that term at all when they talk about their situation.
If that is at all helpful to the committee, that is one piece of information I can pass along.