Let me try to explain what I mean by offsetting which might be better described as offsetting the origin or the source image.
Currently your plugin scales and distributes clones to one side so that your offset (what I might call x-shift) is required to move the clones back into frame.
Taking X to mean the original image and C to mean the clone this is what currently happens:
6 clones with no offset - this is what the current version does.
6 clones with offset 3 - when Clone Scale, x or y Distance or distribution is changed, the scaling and distribution would start from X and the Clones would get progressively scaled or distributed from there. This would mean there would be less need for your offset (x-shift) although you should keep it in.
Some comments on the limits...
Your offset (x-shift) is useful but could do with extending further in both directions.
The Clone Scale only scales smaller but in certain situations it would be great to scale bigger.
The Clones only goes up to 10, perhaps it should go up to 11
A bonus side effect of the Automask is that you get fading in the clones if the contrast is adjusted downwards.