If the cooling system is configured properly you should be able to maintain a 180˚ coolant temperature
almost anywhere you would likely go.
Antifreeze is more than just
antifreeze today. There are lubricants and any number of other additives added to the product. Properly configured your cooling system should easily be able hold the engine temps to a 180˚ coolant temperature. If you want to have protection from boiling just raising the pressure on the radiator cap will do that.
I think your idea about taking the "steps approach" is the way to engage this puzzle. Do one thing at a time, wait to see what kind of results it produces. Based on what you see decide your next move. The everything at once solution set just guarantees you are going to be in the barrel longer than you need be.
An unsolicited perspective;
If the engine is overheating at idle it is talking to you. It could be lean, it could be a timing issue, it could be an air leak somewhere in the intake tract. Properly timed, with adequate fuel, an engine should not overheat at idle.