Morning,
The temps your seeing are pretty much normal. Second fan is supposed to kick in at 220. You can add additives to your coolant like wetter water and such. I've heard they help some. Best thing is to wire a switch to your aux fan so you can turn it on earlier if your worried. Also I would change the thermostat to around 180. Keeps the coolant in the radiator a little longer to let it cool by slowing down the flow. Make sure you have no trash between the the A/C condensor and rad., being a bottom feeder they tend to pick up a lot of trash in that area. The temps that these run at are scarry but that's the way GM designed them. For more info check out Corvette Forum lots of great info there like here.
Save the wave! C-ya