Sounds like managing too many SKUs is the problem.
I don't own a business, but my solution would be:
-Only 2 barrel channels and ditch the factory contour.
-All railed stocks get milled for the Arca/pic Spartan/pic as they can then take any rail. Create a drop in plug for the counterbore Spartan hole.
-Charge extra for any flushcup instal other than standard and install the variations at UM. Charge extra for sling swivels and install at UM. No flushcups on railed stocks would also be extra, call it a customization charge.
Now, you have reduced it to 4 variations total arriving from Stocky's. Some people will whine, that is life.
Edit: 8 Tikka variations given left and right handed.
Rem 700 footprint would be 24 SKUs given short, medium, and long actions. This could be reduced to 16 if medium actions were dropped (or charge a customization fee as mediums are a solution to nothing anyway).