Final(?) update: launching from Steam and loading a save game works as long as anti-aliasing is turned off. Setting 'run as admin' is not required. Do you wish to have me gather any more information, including possibly a save game file?
No changes until I turned off anti-aliasing (from x2) and then running the .exe directly (not as admin) rather than thru Steam - then it works... Steam launch still gets CtD on loading (any) save game, including with overlay turned off. Next I tried setting 'run as admin' on the .exe and running from Steam... and it worked! But only with anti-aliasing turned off.
Oh! There are crash files (.mdmp) left in the install directory after uninstall! I will keep one aside just in case you want to see it...
Mods? I haven't even considered mods... I've been running clean. I'll retry as admin after fully wiping and reinstall and using low graphics preset with no overlays and report back here.
I've already done all recommended troubleshooting / fix activities (update drivers, reinstall DirectX, reinstall vcredist, verify files in Steam, rename game files folder, etc.) Multiple times I have started a new game and everything is fine until I save the game and then load it, at which point the screen "generating world" comes up and runs to the end of the progress bar and crashes to desktop - no crash logger option presents itself. This is consistent.