I think one factor that isn't mentioned often is that Taiwan is a democracy with a ton of special interests, and shipping companies and fisherman are some of the most powerful forces. They will fight tooth and nail to prevent extensive mining since it would cause a major hindrance to their operations. Considering the amount of traffic around Taiwan's eastern most ports, and the space needed for large cargo vessels need to operate and how dependent Taiwan is on exports, minimum mining can occur before the scenario. Example, an Evergreen G Class weighs 240k tons and needs 10 miles to turn 90 degrees, the buffer area required would make that field useless. In addition the prospect of an accident with say an oil tanker, would have tragic environmental consequences and get a lot of pushback. Combining fishing grounds and PLAN ships will only have to be worried about mines that can be deployed by systems like HIMARS and whatever planes and ships can sneak into the strait. If for some reason Taiwan manages to get a large minefield nearby, the PLA can just wait for Taiwan's export economy to collapse and get a government more willing to negotiate during the next election.
In addition unlike in the KMT era, citizens in Taiwan now have recourse and say in military matters. Who is going to want to risk their multi million USD apartment getting blown up when the military wants to put an unmanned turret nearby, that's just begging to be a victim of collateral damage. you will see NIMBYS that will limit where Taiwanese forces can deploy.
In addition unlike in the KMT era, citizens in Taiwan now have recourse and say in military matters. Who is going to want to risk their multi million USD apartment getting blown up when the military wants to put an unmanned turret nearby, that's just begging to be a victim of collateral damage. you will see NIMBYS that will limit where Taiwanese forces can deploy.