I've used baby beehinds fitteds for the majority of Calebs life and they work fine, even when he was doing 14 hours overnight (*sigh* I wish these days...) The nappy was sopping in the morning but it never leaked out of the cover.

I also have a wild child and have been really happy with it. They are more expensive but if you are having to do a full bed strip and wash almost every night then it would be worth it and her only being 6 months you would get your moneys worth for sure.

Putting a cloth over a sposie could work alright but tbh I'd prefer just the cloth and wack in an extra booster

I use several different covers. Fleece, PUL and wool. Whatever is clean really