An emerging, promising set of features. Couples regular overlay functions with some more interesting, experimental stuff...

Here's a girl with some slavetats. 

Nothing unusual there. However, these tats were all applied dynamically without any stored positional data! And viola, no trampling or overlap (Ok there's a little bit of overlap but that's because I set it to allow a 10% overlap for a more cluttered look). There's no need for jsons with "this texture fits with this texture. But this other texture doesn't fit with that texture". There are jsons but they are 'description' jsons only. They allow selecting overlays based on set keywords. You can also request tattoos with a certain word or phrase. Additionally you can read back the text and keywords of applied tattoos in game via papyrus. The table on the left are the keywords associated with the tats. The table on the right is the actual text. These lists were pulled in game. 

Now look at this. In a feeble attempt at modesty our poor PC has equipped some clothes. Now, thanks to the armor cover module, she has reduced the amount of tats visible to others. See how the tables have been reduced. I've allowed any tat more than 60% exposed to be 'seen'. Notice how the lists have reduced. Better cover up that tat that says you're a 10 septim whore. Someone might take you up on your offer...

And sure here's some 'themes' provided by keywords while I'm at it. This is testing so I've basically asked the system to fill each area completely until either there's no space left, no tats left that fit, or the overlay layers are exhausted. 

Abuse: 

Cum: 

Horse:

Edit: Just realized I've been hitting the overlay limit for body & face with the above. Ah well.... Here a couple with the layer count increased so you get an idea of the density it's capable of without making things look muddled. It's again set for a 10% overlap. But you can also specify a gap if you want: 

Left: I've asked the system to fill the face area with exact match for the word 'Whore'. 
Right: I've asked for any tat with the word 'Whore' anywhere in it. 

You can also request a tattoo that fits existing tattoos for a specific region. Regions are subdivisions of the usual RaceMenu 'areas'. 
And you can apply keyword and word filters on top. 

You can also request a tat that would be visible a certain amount based on the current outfit. Here is an all area fill with a tattoo visibility of 80% desired while wearing the tavern outfit. Notice where the clothes covered didn't get any tats.