M5, sorry for not being clear on hill size. I have feeling hill is optically heavy compared to size of the crown of the trees. You can help it by enlarging slab like Grimmy is suggesting, I agree it can work to some extent. Half inch smaller hill could be sufficient, but I see only picture. Obviously in reality it could look differently.
I do not have experience with this particular species but looking on web it can be plated in relatively small amounts of soil. As I wrote earlier, I understand it is in your possession shortly so you cant rush it too much.
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