Any way to export DNxHD with a compressed alpha?

Did this get thrown out when they updated the codec? I'm running CC 2017

I'm trying to export a very simple animation that should only be about 300MB with a compressed alpha, uncompressed it's coming out to 3.5 gb. Any way to get it out of Premiere at a smaller size?

I'm on PC so I can't do Prores 4444 also I can't export Cineform because those don't import into the Avid that I'm sending these shots to.

Thanks