Try the suggestions offered. Then try changing line to PP and see what happens. I reckon you will have less problems after that. But only a field test can confirm. Please keep us updated.....

To improve the lure flight u have a use the right lure weight for the rod to load up in the cast. 
If the rod dont bend much during the cast it's too stiff and not helping to punch out the lure in the beginning of the cast. Theres a possible chance of the knot forming in the first split seconds of the cast, example after the knot leave the tip it will follow by the wind-knot sound.

Try diff lure to find the right weight for the set up, that's why many Fisho do casting before the trip to get the best lure match. 

or thinner leader or knot to prevent stoppage when gliding out of the guides.(this u have tried and it's not helping) 

A stiffer main line (suggested by Steve71)

Slack line while retrieving doesn't mean u have to shorten the stroke.. 
It means during the cranking back or the retrieving after twitch or stroke... Move your rod tip slower and let the reel pick up the line along the way... (Move Rod at the sametime crank along the way)
And not rod tip first then crank the slack line.. 
Maintaining a very light tension on the lure(not to the extend of moving the lure).. Lesser belly on the line better laying on the spool. 

This are just some ways to prevent wind knot.. 
But during actual fishing environment we must adapt fast so that it rise the chance of catching fish.. 
But ultimately "shit happens" sometime but not everytime. 
Hope this helps

Hey guys, I just came back from a trip.

Had got a spare spool n load with a "Ang mo" brand braided line for this time. Wind knot happened ONCE only.

Try using back the other spool with castman, wind knot happened many times till give up.

I managed to take my 4020H for casting last weekend. I paired it with the Lightcast 73H with PE3 Sunline on a SOM 4000 spool. I was casting 60gm to 80gm lures with zero wind knots. Everything else being equal, I truly believe the line texture plays a part. Very thin and light lines are more prone to wind knots. I will use the original shallow spool to cast this week and update on the out come.

If you worry that some of the above suggestions are a tad too technical to apply, just try changing to a stiffer line. It should help.