Where does an emissive quad produce light?

I'm having a ton of trouble with an emissive material I'm trying to add to my scene. Everything is using baked lighting, with a few spots and point lights scattered over the scene. What I want to add is a sort-of neon-glowing sign on a wall, and I'd like to have its soft pink glow baked on to the wall it hangs upon.

However, I'm not sure how I should set it up. I'm wondering, do I need a duplicate (mirrored), back-facing quad for emission, or will the one quad emit from both sides? No matter what direction I turn the quad, I see no change in lighting. I also tried using the scene view in emissive display mode, but couldn't discern any changes as I played with all the settings. The quad is static, as is everything else I want it to be baked upon.

I've spent the last hour adjusting, baking, and seeing nothing change. I've tried cranking up the multiplier to 99x, which creates heavy artifacts on the quad itself but doesn't seem to affect any surrounding geometry.

I'm trying to use emissive map, but I've also tried removing it, turning my quad into a big white rectangle. But that rectangle still seems to add no lighting to the Baked GI.

I'm really lost on what to try next. I hope someone has done something like this before, and could illuminate me on it (pun intended.)