Making toddlers room as dark as possible - help!

[intranquillite]

My toddler is waking up earlier and earlier at the moment and I wonder if it’s his blinds/curtain being too light. It’s also daylight savings soon so I know it will get worse!
We have slanted/angled window casings which makes life a bit more difficult - we got new thick Roman blinds in all rooms when we moved in, with an extra blackout layer sewn in. Curtains are technically kids “blackout” ones from John Lewis but still v light.
However as you can see from the picture it’s still got a huge amount of light coming in at the sides and top.
I don’t want to use the temporary plastic blackout blinds as a long term solution as his room gets very hot; I’ve tried a stick on one from ikea earlier and it pulled paint off the wall and didn’t stick!
Not so keen on replacing our new blinds but happy to change curtains/add things. Would a pelmet work?
Any ideas or advice welcome please!

I used to get some ones that folded out and suckered to the window. You could consider something like that?

Pelmet with a curtain rail that curves and goes all the way to the wall, then thick fill length black out curtains.

So something like this https://www.dunelm.com/product/room-darkening-blackout-25-28mm-metal-extendable-curtain-pole-1000149687?defaultSkuId=30883255&utm_source=google&utm_medium=cpc&utm_campaign=Curtains_Poles-PMax_%5BGOO-PLA-CURTPOLE-POLES%5D&gad_source=1&gclid=CjwKCAjwzN-vBhAkEiwAYiO7oICjq-aFii383YIm_0h8ntvV-NKwcJO1OcpMs3Oo48PHOsjnXcYlgxoCx_UQAvD_BwE&gclsrc=aw.ds

We have the privacy reflective window film because it does heat reduction.
It does also make the room a bit darker

We used some old blackout linings, cut them to the exact inner window measurements and use velcro to stick them up each evening. Not particularly pretty but it works better than anything else and we have tried a lot!

I used the travel gro blinds for the months where it is exceptionally light early. It was a pain taking it down/putting it up each day but so worth it for their sleep and mine!