I have exactly the same experience as Magnusfrost described. Two options for my head and PSVR headset:
(1) Strap fully around the head and bottom of the display is making a gap that not only passes the external light but also makes the display not sharp.
(2) Strap way up on the head and display becomes sharp and filters properly external light but implies uncomfortable feeling that in a few seconds it could drop off my head.
Developed solution:
I know this looks crazy but it works. I took another elastic strap from my head flashlight and: (a) Put PSVR strap down as it should be to feel comfortable (then the bottom of the display is far away from my nose (b) Put the second strap in such a way that it doesn't hide any of the 5 front lights of the display but is positioned on the bottom of it and goes around my head above the PSVR strap, so the bottom of the display fits perfectly to the nose.
Summary: No external light inside.

Sharp picture on the display.

No feeling of potential headset dropout.

A shame that equipment that costs $300 requires such crazy proprietary solutions
