Note that Photo AI also has the option to save the processed Raw files as TIFF, which in my test actually resulted in a smaller filesize than the same image saved as a DNG -- and the TIFF previews full sized within Photo Mechanic.
For myself, I only use Photo AI as a plugin within Photoshop since there is always at least some further tweaking needed, so I'm saving those as PSDs which also preview well in PM.
Maybe those are options as well?
Mick