For legislatures, I think simply leaving the seats vacant until the next regular election would be reasonable. It would encourage both the parties and the voters to take the health and ethics of candidates a bit more seriously if they knew it wouldn't be easily filled if there was a problem. At most, a provision to suspend their participation while part of an executive cabinet if making it easier for legislators to switch to the executive branch by allowing to return to their former function if their term hasn't already expired by the time they leave the cabinet.
Bur who would represent a district that might be vacant for as much as two years? The constituents have the legitimate expectation of a voice in the form of a vote in the assembly as well as an advocate to introduce and promote legislation of interest to the district.
Then they should elect someone who they can count on remaining in office for a full term. At most your argument is an argument for multi-member districts.
