Heavy Arri Alexa render files, Final Cut Pro

Hi

I wonder if somebody can help me. I'm starting a music video shot on Alexa, the rushes themselves on my drive are around 300Gb.
What I've done so far is created a fcp project, dragged the footage into the timeline and applied Nick Shaw's LUT. I then started rendering the timeline, but when I got back it turns out that my external hard drive is full and my render files weight around 300 Gb, leaving me with only 2Gb free on the hard drive.

I'm now moving the project to a new 1Tb drive and wondering if it's going to be enough?
Anybody, who edited alexia footage faced the same problem. I'm aware that alexia files are very heavy, but I haven't even started editing itself.

Thanks!
Yana