@Damraska Doug, that sounds like an excellent start on a Pz IV company! I too have purchased Pz IV based on “government logic” → why buy one, when you can have two for twice the cost? Part of the hobby fun is collecting too. Plus with so many kit manufacturers I can’t show favoritism until after trying their products!
Indy, L&L and the V-word tracks, what a topic. Vinyl is better for making LP’s than model tank tracks. Actually, I’m OK if it’s the 90’s later Tamiya vinyl on certain vehicles like a T-72 with side skirts. I like properly engineered individual link best. Great point about the KO pin placement. The old Tamiya, Dragon & Italeri vinyl tracks are trash.
Please share info details on Mr Surfacer, what’s so toxic about it? MEK, Xylene or something really nasty? 
Other than Floquil its one of the very few products I actually like! 
Regarding flat head screws, Lion Roar or Lion Mark made an excellent .9mm one perfect for 1/35 scale. It disappeared but another manufacturer makes them now bought a few packs on Hobby Easy before the pandemic. Aber makes a PE version but that’s not as trick as the actual screw heads are because the PE needs deburred usually etc.
Homemade is also an option Vintage Italeri Pz IV G - build kit bash has my attempt at scratch flat screw heads.
Drill hole for screw head, Cut slot in styene rod & Plug hole. Using a chopper to keep the end of the rod flush really helps. Cut slot with fresh blade etc.
Thank you for checkout the thread and kind words! When I’m back home will try to remember to find and share the aftermarket company’s name that makes the .9mm screw heads.