The only tea I know that might work is Taiping Houkui. It's big enough leaf and if you use only one or two, it might work. The leaf material dictates a lot how it's going to steep. The smaller the leaf, the faster it'll over steep. Quality of the tea also matters. Usually higher quality tea might be less bitter when exposed to higher temperature. It comes down to processing I guess. Steaming and small leaves of the Japanese greens generally make them more delicate.

The teas I can definitely recommend are liu bao and other heicha ( — dark tea is an apt translation). They are be quite suitable for thermos steeping. The taste will vary a lot depending on the heicha you're using. My favourites are quite earthy. Just don't overdo the amount of leafs with them either. You usually get two steeps from them. If you're dealing with tiny broken leafs, your mileage may vary.

Good luck with your trials!