It sounds like you want different output dimensions, NOT different crops. In other words, if I understand correctly, you want the same portion of the image and same shape (which is what the "crop" is defining), you just want a few different size outputs.
If that's correct, then it's easy to do in Lightroom, but in ACR proper - I dunno..
Here's my best guess - with the crop drawn on your image, if you right-click within the cropped area, a list of crop sizes will be displayed. Pick the one you want. OR, better yet, create a Preset in ACR for the sizes you use. You can also try creating a template as a Smart Object and use the Replace Contents command to insert the next photo. Send that to the print queu and go to the next template and repeat as needed. Also, are you using the Image Processor Pro version, available free at www.russellsmith.com. The only other thing I can think of is to write your own script using variables, a spread sheet and templates. Ben Willmore has a class on the subject so maybe that will make things workable. The class is offered on www.creativelive.com or Ben's FaceBook page or web site, www.digitalmastery.com should provide the solution.
Are all the file specs that you set up in Image Processor available in the Save Image button in ACR?
If so, your steps could look like this:
- With Crop tool, set image to correct proportions.
- In Workflow Options, choose preset you made for 10x8.
- Click Save Image button, choose preset you made for format/file specs, click Save.
- While that is processing in the background, repeat steps 2-3 for the next two image dimensions. The odd one is the 8x6 dimension because it doesn't match the proportions of the first two, so for that one you'd have to go back to step 1.
If you can accomplish your entire workflow in Camera Raw, and if I haven't misunderstood what you need, this could end up being a more efficient workflow overall by saving the trip out to Image Processor.
Of course, this assumes you've set up presets (a relatively new ACR feature) for your standard dimensions and file specs so that you can keep the number of clicks to a minimum.