Oh dear. Looks like Hughie v. King might be moved up a few weeks.
Since there is no set rule by the Constitution that requires a special election
Actually there is:
Article I, Section 6, Clause 2:
"...If any district Senate seat becomes vacant, a special election shall be held within one week to fill in the vacancy..."
There's no getting around these requirements in my opinion; You cannot just leave this open like we did with Steven since it leaves the Senate down to 9 Senators until 4th March, which is nearly 6 weeks. And there is certainly no way you can have "interim" appointments from anybody since Regional seats no longer exist and there certainly is no provision or precedent to have the VP appoint an interim.