Currently, I'd have to install Light Overlay to have this functionality, which seems redundant and wasteful considering this mod already has the capability to show light levels, just not as numbers.

Seconded! Doing the same thing here. Have both overlay mods installed, but currently have this one's light overlay hotkey disabled. Really hoping for this feature in the future so I can toss the other mod.
This mod also seems to work better with optifine too which causes issues with the light overlay mod. Which they've already said they won't fix. Just another reason to toss it.
Edit: Just discovered the Torch Optimizer mod that does numbered light level indicators. Works perfectly with optifine/shaders and can even indicate where you should place torches to optimize lighting with minimal resources.

@NightOps007 Just so you know, they might have said they won't fix the issue with Optifine because fixing Optifine-related issues seemingly is a major PITA and sometimes isn't even possible due to the nature of Optifine's game modifications.

Torch Optimizer looks cool, thanks for adding that in as an edit!