Minecraft – n easy way to calculate a block’s light level

I'm trying to build a house out of ice, for no other reason than sheer novelty. (Though perhaps also because I want to use my Silktouch I pickaxe)

Ice is a very finicky building material, prone to melting when exposed to the "normal" light levels of a torch. Specifically, if any adjacent block attains a light level of 12 from anything other than direct sunlight, it will melt.

And so, I reach a conundrum. I want to light my house enough so that I can see while walking through it, and also enough to completely prevent mobs from spawning inside my house. This means I want to keep the light level approximately between 8 and 11: easy enough to do someplaces, but a pain in the butt to calculate for every potential spawnable square.

Is there some way to identify the light level of a block without the tediousness of manually calculating each block's light level? I'd prefer an external tool over a mod, but I'm willing to consider the latter anyway.