Might I make two suggestions?

1. Try untucking the waistcoat. They are meant to be worn over the kilt, and thus hiding the top of the kilt.

2. While others have made positive comments about your choice of neckwear, I cannot say I am a fan of such...well, I just don't know what to call it!. You've ruled out a jabot ( for some reason ); others have suggested a cravat. My suggestion would be to just wear a black bow tie--tied by your own hands. That would look quite sharp!