What setup do I need to record and render at the same time?
I assume you record video game footage?
Recording and rendering on one machine is something I wouldn't recommend with a regular PC if you play modern games that take a lot of your CPU and GPU resources.

I usually recommend getting an SSD but in this case it seems you are heavily CPU limited.
You could theoretically encode on the GPU but I'm not sure if that will ease the workload all that much to be able to play games as you need your GPU to play games aswell and usually GPU encoding produces worse results than CPU encoding because of the way the codec is implemented for GPU encoding.

What I would do in your case is either render on your MacBook, rendering over the network shouldn't be too bad in this case as your MacBook will be CPU limited aswell.
Or you don't do the final encode of your videos with Premiere/AME but use a different h264 encoder called x264 which is a LOT easier on the CPU and with the right settings could potentially used while you play games. x264 is by far the fastest and most efficient h264 encoder today.

You would first render your cut videos in a lossless codec that doesn't takes very little CPU usage but be sure to not render to the disk that your game runs on, as a lossless codec will be very I/O heavy.

Alternatively if all you do is cut your videos in to 20 min pieces without any other creative decisions other than splitting up your videos at every 20min interval you could automate everything and ditch Premiere all together and just use FFmpeg which also integrates x264 so you can cut your videos automatically there and encode to h264 all at the same time.

You could theoretically also upload automatically after rendering if you are bit into programming and do all at night without supervising anything. That would free your pc up for recording during day. That can of course only work if you don't already need all night to upload the encoded videos.

There might be more viable solutions to your problems but that would need a bit more info from you. What do you record? What are you doing in Premiere exactly to the videos other than cutting? What are the specs of your computer?