this tree has lots of potential. its nebari immediately reminded me of the tree in the first attached photo
I would put this tree in a grow box, and develop the nebari on the full circumference, letting some of the grafted scions grow fairly large to fill in the gaps in the nebari. this will create wounds in the nebari as in the 2nd photo, but they will heal. i'd be careful not to let these new 'trunks' shade-out your sango kaku
I like the last photo attached here as a possible front. i'd develop the new leader, first branch on the right, second branch on the left
a lot of very promising long term potential! when you win the beauty contest, dedicate your award to
@Woocash