I think that:-
i - That's really unlikely
ii - You've really had to stretch
Given that your scenario is possible, not plausible, then, under those circumstances, I'd be happy to do it all again.
I'd suggest it's almost an impossibility - has it ever happened under the current system when one party has had a majority?
I really don't think you understand what you are saying. STV is a system of voting for MPs. It is more proportionate than FPTP, and is therefore likely to produce a mix of MPs rather closer to the percentage of votes the parties garner than FPTP. In almost every country where any system of proportional representation is used, coalitions are the norm, not the exception. Your suggestion would lead to more, not fewer, coalitions: the very opposite of your stated aim. You might want to do some reading.