As I can see it, to me the problem is more a question of volume than a matter of number of trees.
If you look at the base...
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1,3 & 4 seem to be aligned, which gives an impression of flatness.
1,2 & 3 seem connected, while 4 looks separated from the rest.
But maybe cutting off - or making a jin of 3 could be another interesting solution:
- 3 trunks are less monotonous than 4
- 1-2-(gap)-4 would also be less monotonous
- 1-2-4 would be 3-D
Like:
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