Just a thought...though I think many might not approve...but...why not model turrets with a commander figure just popping his head out of open hatches? It would be SO much easier to decapitate and fill in the hatch instead of drilling, cutting down figure, adding hatch lids, etc. For Brit armour un-buttoned is almost essential...German, US...less so but useful. Really big hatches, such as on Crusaders, etc. would b difficult to cut back and fill in...BUT they were almost always open...and trying to replicate an open hatch on a Crusader II... :'(
I think that would be a nice option, as well as a standard hatch cover to replace the guy in it instead, if desired.
With a little ingenuity, and some very small magnets, you could swap them out, as needed/desired.
I think the logistics of altering and remoulding all of our tank turrets would make this one unviable I'm afraid! We could probably do with some more tank commander torso options for the ranges, but I think that would be about the best we could do. Maybe some turret hatches for folks to glue behind the torsos? They'd be small and fiddly but it's doable.
Cast a commander in the turret ring. You file of the turret hatch and stick the new one on.