Will his anger in losing the nomination override any sense of rationality he possesses?

I suppose that that comes down to what you feel of Trumps personality. For my money, I do think he would resist the urge. Yes, he is driven by ego and has done bizarre shit because of it. But Ego is a lot easier to read than people give it credit for, and the only way I see him pulling something like that would be if he had some trick up his sleeve to make it work.

Being a loser, who then causes even bigger losing to someone a lot of his supports actually have respect for, would destroy him, which would bruise his ego a whole lot more than just losing and then fuming in the corner. Especially if he can turn it into something that he thinks he can win on ("DeSantis was going to be a weak RINO, but I helped pull him in a more based direction folks!")