It's called an accusump.
Canton Racing Products
1, 2 & 3 quart accumulators. You would have to insulate it yourself. Electric valves are available.
Normally they are used with drysump oil systems with a large resovoir. The small cooling resovoir may present a problem. There may not be enough volume to empty the accusump.
A system with a pressurized "overflow" bottle may be the way to go. You could increase the size of it with an auxillary tank with an upper & lower hoses. You need to make sure the tank has air in it.
Don