You always have the option of using a seed or template file when exporting to CAD. I'd suggest you create a base drawing with units (and any other AutoCAD configuration settings) defined.
I am having the same problem (see: https://community.esri.com/message/446321#446321
I am using a seed file because I am using block definitions for my point features. The drawing units in the seed file have been defined as: Length Type: "Architectural" and Units: "Inches" (or Length Type: "Architectural" and Units: "Feet"-which CAD clearly says it does not like), but the scale is still exported wrong in the CAD interface (it has correct lengths when viewed in GIS).
Is it a problem with the seed file or the tool?