Option to not autocrop/ recentre for asymmetric overlays

[mbfgit]

Is your feature request related to a problem? Please describe.
I use custom overlays which are mostly hex, but have additional non-transparent pixels on one side of the hex (front facing). These are centred correctly based on the hex centre in the overlay+mask, but when saving an image from tokentool, the token is re-centred based on the extents of non-transparent pixels in the overlay, so the resulting token image is not centred w.r.t. the layout in the overlay.

Describe the solution you'd like
It would be nice to have an option to not auto-crop/re-centre overlay/mask if you know your overlay is asymmetric, but centred within the extent of the overlay psd. Either on overlay import or within overlay options would both be fine.

Describe alternatives you've considered
At the moment I'm post-processing each image to shift the content up vertically about 3% within the frame.

Additional context
Example of overlay and token produced without any portrait or background image (the token is 12px shifted down vertically vs where it should be):