Maaan! You've made it way more complex than acheiving some drop should be!
My 2c: A single Kicker Solo-Baric, It truly doesn't matter which "S" model it is, they all slam in the SMALLEST boxes, they were designed for just that. Three woofers in a Del sol seems like it'd cause more actual headaches trying than bassin'!
Good Luck whichever way you go.