Overheating issue or just paranoid?

My 04 silverado tow pig has developed an interesting coolant temp thing this week.  It is a 4.8 with 150K miles, coolant a year old and fan clutch done this summer.  Driving around town in temps around 40 F the scangage gets up to 210-215.  If I stop and let it idle or get above 40 mph it drops to 190-195.  I pushed it hard on a steep 1/2 mile hill and the temp was a steady 195.  To play it safe I put in a new fan clutch and no change.  The dash gage reads below 210 all the time.  Verified the scangage number with an OBD reader and they match.

Is this the beginning of a water pump or thermostat failure? We are towing a load 1000+ miles in a month, would prefer to resolve this first.

Could be a bad new fan clutch.  Most aftermarket ones are kinda junky.

Did it ever run hot? Electric fan models don't even kick the fans on until 220-230F, and overheat protection mode isn't until 245-255 or so. 215 is normal operating temperature.

My theory is if it is not steaming it's not overheating.

Put a piece of tape on the dash over the temp gauge, your going to hit the car in front of you because you're paying too much attention to the temp gauge. 

I expect that at 150k the radiator is caked, has that been replaced?

Really though, if it does not steam when you hammer it you are good to go.

Have not had the rad cleaned but when I changed coolant it looked pretty good.  I blast the rad outside every 6 months, but will take off the shroud and hit it with compressed air to see what blows thru.  The new fan clutch has about the same air flow, I doubt this is the issue.  Have had the truck for 3 years and the temps have been pretty consistent, 190s regardless of weather.  almost never over 210 even towing uphill in 90 degree heat.

I am leaning towards changing the thermostat, and unplugging the scangage.  But I would be happier getting the numbers back to where they were.  If it runs warm in 40 degrees empty what will happed at 65 with a trailer and full load in the bed?

Which part of your question related to overheating?  I saw nothing that would concern me in your original post.

My 07 Silverado ran 210 to 215 all the time. That is normal. 

My 2000 XJ also runs 210. The electric fan doesn't kick in until 217. 

The days of 180 to 195 engine temps are long gone. 

06 4.8 CC 2wd. 210 is the normal running temp for ours since 2008 when I got my scanner. Electric fans come on at 210.

Are you sure this is an 04? 04-06 should have gotten electric fans. 99-03 had a fan and clutch.

It is an 04. 04 had a fan, when I looked it up there was one listed. 

 Normal can vary, this truck normally runs 190 to 200.  It still does, as long as speed is over 40.  As soon as it drops to 25 temps creeps up to 210.  If it always ran 210 that would be fine.  But I think there may be a cause for the increase and will continue to look.  Tomorrow I will drain and flush the system, and try to clean the radiator fins.  Thursday a new thermostat and coolant get delivered.  

My original post asked if this is a sign of a thermostat or water pump failing.  The water pump looks new but was done before I bought it.  

Can confirm 04 had a fan, converted one to electric with PCM control for a plow truck.  (The plow prevents airflow through the radiator, so the clutch fan was not getting any hot air to bootstrap the thermostatic clutch)  The OE electric fan setup uses the mounts that the existing radiator uses so I had to use a radiator from a different model, forget if it was an '05-up or just a one ton.  They all use the same core support.  Added three relays wired up like a Corvette uses, added the terminals in the PCM, turned on electric fan capability with HPTuner, and no more running 240 down the highway with the plow installed.

Honestly I don't see a problem.  At lower speeds you do not get as much airflow, at higher speeds it will hover around the thermostat temp.

It's not a bad idea to backflush the radiator and condenser with water.  An amazing amount of leaves and debris can also get between the radiator and condenser and need to be removed manually.

I don't see a problem with your temps at all.  If you said 235, I might wonder, but 215 is where my 06 Express van lives permanently.  The way yours is acting does suggest an airflow issue, but doubtful it's a fan.  More likely junk/debris.  Could also be a stat that is wussy.  Not fully opening OR closing.