If Trump refuses to go along with needed debate format changes, the debates should be held with Biden at one podium, and other one empty. It least we would then get some coherent picture of what Biden is proposing.

Well. That answers that question.
Trump has no intention of following debate rules so to have effect the commission response has to be somewhat extreme -- likely not just cut off the Mic, but physically isolate the speakers in booths.
And when Trump whines and backs out, make it clear that it's his own fault and give over the time to Biden.

I don't expect that kind of clarity from American media but I can forlornly wish.

looked Exactly like the self-important puffed-up toad he is...i say let him bluster!

Trump's life has revolved around insisting that rules are only for "losers".