Yes, you can build up an engine/editor instance and then use it without keeping all the intermediate object files on disk.
Studios frequently do this for artists, who don’t need to build the code from scratch, but instead just get the latest build occasionally.
That being said, I highly recommend getting a second disk – a 1 or 2 TB SSD to connect via SATA or M.2 (if your motherboard has an available socket( is pretty affordable these days, and will massively help. Something like this:
or this: