I'm learning from your tips!
I haven't used the extender as yet but I need to get it out of the box and wash it and have it there to try it.
I've not made any more cakes since the one and only. Yesterday daughter and I made a bean chilli type concoction and baked sweet potato (the Kumara) in very thin slices in the oven. Just seasoned them with a light dusting of spices to make them savory. They were used instead of corn chips. Delicious, but the oven is a bit small so we needed to cook them in several batches. No drama.
I'm thinking I'm using the high rack too much. I find it difficult to get the top rack out of the oven when it's really hot is the problem. Working on that.