Nuria, regarding the IP addresses specifically (not the proxy, for which, I'll need more time to go through the use-cases we've had and see if we can find work-arounds if we hash proxy information):
Have we considered in the past to create at least two levels of access when it comes to the IP addresses? From what you describe, it is clear to me that your team will need to have access to raw IPs for a certain period of time. It may be the case that no one else uses that information (for all of the use-cases of the research I've been involved in, hashed IP works as well, as long as we have geolocation available to us). By creating two layers of access, we can make sure that your team has access to raw IP while everyone else doesn't. Is this an option?
And one suggestion: if we want to reconsider the way we provide access to IP address, I'd like to suggest that we step back and reconsider the way we give access to other fields in the webrequest logs as well. This will be a longer process, but it may be worthwhile. For example, if we decide that access to raw IP should be limited even further, do we want to have the same restrictions applied to access to UAs? It's not obvious to me that the answer should be no.
Best,
Leila