On a semi-related note, you seem to have some familiarity with cad programs, so Autodesk Fusion 360 might be of interest to you. There is a fee 30 day download, and hobbyists can register it for free (no time limit) if you are using it as a hobby or in a business making less than $100,000 a year.
Fusion 360 is both cad and cam so you can design a part on there and use that to create the gcode directly. My xcarve (but I finally ordered it!) has not arrived yet, so I have not personally used it, but youtube videos I have seen show them exporting gcode in grbl format and using a gcode sender (not sure which one of the top of my head). Fusion 360 does have a learning curve, like everything, but there are a fair amount of good youtube videos for it.
Hope that helps, and apologies if it does not. Best of luck!