Heh. Actually, I'd thought about cleansing the temple of Amaunator under the temple district. So much, in fact, that I actually sat down and figured out what would be involved. I originally considered the temple in the Umar Hills, but that is so heavily involved in other mods and other quests that I decided that I didn't want to touch it, just to preserve compatibility, if not for logistical reasons.
But there are logistical considerations for the temple under the the Temple district as well.
At first, I thought about making them look "Lathanderized." That would require redoing four areas, one enormous, two big, one small. Not going to happen.
First of all, access through the sewers? Uh, no, that won't do at all. These are Lathandrites, don't forget. They don't do grime. And that whole Cult of the Eyeless area, the crypt area where Sassar was, and the area with the bridge... there's no way those could be fixed up to look nice without a complete overhaul.
However, there are two unused buildingings in the actual area of the Amaunator temple itself. Currently, they've got info points that say that there's nothing inside, but they could be made up as transition areas, perhaps to a location within the temple of Lathander.
But that's all just speculation. There's still most of a mod to write.