Head chairs are not appropriate for a table and area this size. They fit better with a separate dining room and a table of 8+

Besides you already have two types of seating at this table and now you want to add a third type???? Do you even have the room for two more chairs?

You could add another bench and place the two chairs with backs at either end of the table. 86 the table runner. They are like modern doilies.

You have no leg room for head chairs.

There is no space at the ends for chairs the table allows no foot space and I have to tell you bench seating at a DR table is awful.