Run it the way it is, the turbo will heat it up and the inter cooler will cool it down. It takes extremely cold weather to cause any issues. Unless you live in the far North, high Altitude, Alaska, or Canada you should not need to block off the radiator. If you live in one of those areas the people who live there should know all the options if there are any better than a piece of cardboard.
In a perfect situation, most Diesels prefer 60F, enjoy that when it happens.
Some of use use fuel coolers to enhance the lubricity of the diesel and reduce the power loss in hot conditions.
I have found out the fuel heater is useless at any temp over -10F, even with my over kill fuel cooler that is twice the size needed.
If you want to experiment with running a diesel engine hotter, pick one that is bullet proof like an old Mercedes inline engine with a cast iron head. What some have done on those old beasts is run straight Propylene Glycol, boiled out all the water (just keep adding to the cooling system until you need to quit adding more), run a ZERO pressure radiator cap, and rig up a 250F to 275F thermostat. I don't know what engine oil they use, but the fuel economy goes up. Cummins built a test engine out of ceramic that had no cooling system for the Military, have not heard any more on that one. Doing this on an aluminum head engine is risky. GDE discussed running higher temps, but you should talk to them if you want to give that a try.