You may have to work with multiple systems. You may have to work with the exterior shutters + window tint + "black out" drapes. Black out blinds do most of the work but there is always a risk of light peaking through.

The single answer that is 100% reliable (sounds childish...but it works) is: Remove the sliding glass door and replace with studs, siding, insulation and drywall = 100% effective. Childish I know...but it is, technically, an option.

Reducing light to "Zero" with a 6' wall of glass is very, very difficult. Very difficult (as you have just experienced). Multiple systems give you the greatest chance of success. If you have 99% success with each system, you have less than 0.33% chance of light coming through. If that 0.33% light is too much, you may have to remove the window and fill the space with 'wall'.

It is easier/cheaper to retro fit a home for bad acoustics than it is to get rid of excess light in a space where 100% lightless is required. And retro fitting for acoustics is a BEAR!

I had luck with wrap around rods hung about six inches each side of the opening and higher than the top of the window. I used two grommet top black out thermal patio panels instead of one so they were very full. Since the rod had a center support the drapes just go to the sides when I want to open them.

have you tried country curtains? they sell a blackout liner.

I already tried blackout liners, however, because the drapes are only 50" wide to cover a space for 100", the sunlight comes through the areas above and below and between the width of the panels.

I'm thinking of installing wrap around rods to keep out the sunlight from the ends. I would have installed a rod on the ceiling but the way the slider is configured, it will not work.

what did you end up doing? I'm having a similar issue but I dont have room for curtains since the door is almost all of the way to the wall on one side.