Preheat oven to 375°.
Remove and discard giblets and neck from hen. Split hen in half lengthwise. Trim excess fat. Starting at neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between skin and meat. Combine juice, oregano, thyme, oil, pepper, and garlic; rub herb mixture under loosened skin and rub over breast and drumsticks.
Line a jelly-roll pan with foil; coat foil with cooking spray. Combine 1 cup water and salt. For each hen half, pat 1 cup salt mixture into a 1/2-inch-thick oval shape on pan. Coat each salt oval with cooking spray; top each with 1 hen half, breast side up. Lightly coat hen halves with cooking spray; pack remaining 3 1/2 cups salt mixture evenly over hen halves.
Bake at 375° for 35 minutes or until a thermometer registers 165°. Tap salt to loosen; discard salt mixture. Discard skin.