I could be wrong, but I thought the turret on the LVT(A)-4 was a relatively small two-man turret. So it's superb rate of fire seems to already account for any advantage of an open turret.
3.6 second reload time is already between 15 (4 seconds) and 20 (3 seconds). Maybe the 75mm gun's reload time should be shortened? But, yes, it seem intuitively reasonable to have at least a small difference in reload time.
Variability of quality isn't coded elsewhere in the game, so I don't see a "crew experience variable" being added. It might be interesting to have a perked crew option, though, similar to a perked ordinance scheme that was once discussed.
That is precisely my point: vary the reload speed by just a wee amount to accommodate the differences in shell size, etc. If the 75mm is 3.6 seconds, then maybe the 76mm could be 4 seconds?
