Usually you’d go with several panels for the right fullness but it can be tedious to open/close - are you open to lined/blackout shades?

2 panels each side. I have that in my living room and I hand stitched the headers only together so they stay together and just have to fiddle with them a bit when closed so I do not get a light gap.

You use mutliple panels not sure what else can be done. The panels should be at min. 2.5 x the width of the rod so in your case at least IMO 3 panels on each side and I would pobably do 4 How much true blackout do you need? I have use lined grommet drapes in many bedrooms with good results ease of opening and closing and never had an issue .

You would still need 4 panels, but with these being so full/meeting tightly, there shouldn’t be any light filtering in. You could also sew them together.

Inside mounted black out blinds would be easier, but may need custom.

As suggested above, I used inside-mount, blackout cellular blinds for my bedroom casement windows. The blinds are mounted as close as possible to the plane of the wall (i.e., away from the window) to minimize contact with the crank. I chose single-cell, blackout Bali blinds because they appeared to have the shortest "stack" to minimize the amount of fabric that extends over the glass when the blinds are open. (While I didn't want them, I couldn't have installed curtains because I have a dresser beneath the windows.)

If you don't want light leaks from the sides of the drapery panels, you'll need drapery rods that curve back to the wall to seal the space.

You'll need 6 panels, 3 on each side.

Without seeing the room it's hard to suggest, but you might want to consider something other than drapery panels. There are blackout cellular shades, blackout Roman shades,

We have inside mount roller shades on our main floor and same on bedroom level but blackout and then curtains.