Losing a small amount of water

Having trouble figuring out where the water is going. Car loses around three ounces/day if we drive the car in hot weather (live in FL) around 2 hours/day. None of the hoses are leaking, and we can't find any water on the ground.

Car definitely loses water. We haven't pressured up the system yet, but even so, we don't think we'll see the leak.

My friend, an amateur wrench, speculates that maybe one of the head gaskets has a tiny leak on the exhaust side.

It is really baffling. If we forget to check the water at least every other day, for say a month, the car can start overheating. We have never let the engine lock up, and the valves sound fine.

There is no oil in the water, no bubbling, no white smoke in the exhaust, car runs smooth (no missing). Any ideas?

Thanks,

Jon