Glad to hear it! It is actually possible with a command line argument -s or --save-location. I'll look to see if I can make it more friendly towards that however, but it may be tricky.
You'll want to make a file called "Cosmic Reach Portable.bat" *in the exact same folder as the exe file*, then edit it in a text editor to write:
@echo off
cd /d %~dp0 "./Cosmic Reach.exe" -s "cosmic-reach-portable"
Then run the Cosmic Reach Portable.bat file instead of the exe. Remember to backup this script so that in future updates you can repeat the same process. If you run into trouble, search how to make batch scripts for windows.
So I tried the method, and it actually worked. It gave the game file a new directory dedicated for save data. However, a Command Prompt window popped up with the line; "The filename, directory name, or volume label syntax is incorrect."
I'm actually using an E drive instead of a D drive, so that may be why.