Auto Increment Column with Document Sets - is this even possible?

Is there any viable out of the box way to create an auto increment column with document sets?

I thought I could use the ID, but I wasn aware that the documents within document sets take up from the "global" ID set of the root folder. 

Now that I've created a few test sets with documents my first three document sets have these IDs 4, 25, 776 :P

I would have been OK with a few gaps due to deletion, but these jumps are not viable.