Welcome to the club. You are far from the first person to go down this rabbit hole of pack building.I understand as well. Now I am happy/angry that I am spending more time making girl packs then actually playing the game!
Now that may be unique. A 3D artist building their own art for the packs directly. I built a pack a few months back that was 60% or more from one 3D artist, but he did not do the images specifically for the pack.Soon about to start creating my girls in 3D modeling software to get correct content for tags. I feel wasting time looking for content that I am not satisfied 100%.
As a non artist without that option I will say that I simply had to learn to accept that I'm rarely going to find coverage for every possible tag in a pack. Some tags are just plain rare. Enema is one of the rarest. Fisting, Rimming, and sometimes some of the farm tags are also rare.
That said, the game is designed to function well even with holes in the coverage, so it's not like you need every single tag covered to have a descent pack.