Making adjustments to a nearby muni's signs ordinance for adoption in this one, which contains a category called "election cycle temporary signs".
It allows them as "extra" signage permissible on any zone lot, restricts their size, and defines the "cycle" by number of days prior and after subject election.
Notes made by a lawyer presenting at a zoning admin conference near here last year include one that says any such time limit on political signs is unconstitutional.
The most basic premise of the model I am using is that each zone lot gets to have at least one sign regardless of its content. My thinking is that the temporary allowance for election cycles would stand up in court by virtue of its temporary status. If a property owner objects to the time limit, then his one sign allowed on a permanent basis would protect his right of expression.