Example 9 is basically what you are doing.
There's no point speculating as to the minutiae here, the example quoted is based on the draft consultation that was put out. The report from the consultation will be out soon and the legislation will be based on that, most likely with a few tweaks.
It is expected that there will be some way to designate somewhere as your main property, at least similarly to how CGT works on your primary residential property. But the safest thing to do as it stands is to push through and complete before the 1st of April.