Flint & steel use only on top of block possible?

I'm making a puzzle-based dungeon and have replaced blocks with custom torches blocks. But even with CanPlaceOn, you're able to use flint on the sides of the block, which lit the floor next to it.

Is there any way to make it top of the block only? With wall posts you can't use the flint on top of it but on its sides, I want the opposite of that. Or any work-around.

I can use slabs around it to prevent clicking on the sides of the block, but it doesn't look good and takes up a lot of needed space.
tweakbox appvalley https://vlc.onl/