Proxy File Size when Converting Red 8k Raw files for workflow

We are setting up workflow to edit a feature film which was shot entirely in Red 8k Raw Files. We will be using the brand new iMac Pro so computing power should not be an issue, however we are trying to determine how much space we will need to prepare with our G-Drive Raid set up. While the math seems like it should be easy, that has proven to not be the case. If anyone has any info on what the conversion ratio is for file size of the proxy files in this case we would greatly appreciate it? I understand that the setting choices and codecs we choose will make a big difference, so we're wondering what the best choice is here to optimize high quality smooth playback during the edit. We have a grand total of 15T of Raw media files, so once the proxy files are linked to them, how much space will be needed to house it all? Ultimately, the consensus is that we keep them all together in the same destination for smooth workflow and to help near the end of the project when we are getting ready to start doing outputs of the film. I've read on some blogs and forums that the proxy files end up being as much as 1/2 or 3/4 the size of the Raw files. That means we need 32T? of space just for this movie to house the media? That seems crazy. We are doing some tests now, but even locating the size of each individual proxy file and then doing the math looking forward is tough.

Thank you!