Interesting thread Jak
There is a saying in bonsai that we should try to look with a beginner's mind. The mind of a beginner has some unique qualities that can easily be lost so there is no need to apologise for these qualities.
Another saying I like is whatever works. Pretty obvious really but you will be amazed at the notion of some people that there is only one way to skin a cat.
I will always remember George helping me do a root over rock and showing me how he uses glad wrap to hold the roots but was sure to state that Ray and himself always like to say whatever works.
I can't see any reason why the rock would not work. We have another member here that has shown how useful cloths pegs can be in weighing branches down and weights are used in other various way's well in bonsai.
The worries about the branch fusing and causing a taper issue may be warranted but as they have not tried it they can't say for sure it will happen. This is a very young tree and it is very possible that any bulge from the fusing would disappear in the not so distant future.
I don't see any great reason to change your tree again but just wanted to remind that a beginner's mind is not something to apologise for. I was a little disappointed you gave in.
I think KC was trying to give practical advice more than filling you in on competition rules

Although in years to come you may find your response to him quite amusing

It's too bad your in such a hurry cause the stories I could tell you, Bushels and baskets of stories, hole crates full of stories. But if you can spare a moment I will tell you one story.