The "working-ground" (kammatthana) of the five hindrances

My question is about the following passage (taken from the section on the five hindrances here ): > One who earnestly aspires to the unshakable deliverance of the mind > should, therefore, **select a definite "working-ground" of a direct and > practical import: a kammatthana[1] in its widest sense, on which the > structure of his entire life should be based.** Holding fast to that > "working-ground," never losing sight of it for long, even this alone > will be a considerable and encouraging progress in the control and > development of the mind, because in that way the directive and > purposive energies of mind will be strengthened considerably. **One who > has chosen the conquest of the five hindrances for a "working-ground"** > should examine which of the five are strongest in one's personal case. > Then one should carefully observe how, and on which occasions, they > usually appear. One should further know the positive forces within > one's own mind by which each of these hindrances can best be countered > and, finally, conquered; and one should also examine one's life for > any opportunity of developing these qualities which, in the following > pages, have been indicated under the headings of the spiritual > faculties (indriya), the factors of absorption (jhananga), and the > factors of enlightenment (bojjhanga). In some cases, subjects of > meditation have been added which will be helpful in overcoming the > respective hindrances. The bolded emphasis is mine. My question is, what is meant by making the "conquest of the five hindrances a working-ground"? Kammatthana is later defined as the subject of meditation (literally meaning "working-ground"). Instructions are given right after the assertion but I am confused as to how one might extend this into everyday life and not merely during meditation. Furthermore, meditation often has some other object of focus (namely, the breath, the movement of the abdomen etc.) does making the five hindrances the working-ground change this? More practically, if a thought arises which is unwholesome (not during a sit, but in everyday life, since it is stated above that we should make the "structure of [our] entire life" based on the working-ground) should we try to categorize the thought into one of the hindrances, then accept it merely as a thought, as part of a process which does not constitute our identity and then watch it impassively until it fades? Or how should we deal them?