I don't know what your setup looks like but it is always an option to run the pipe up to the top of the studs and then outside the wall. When you put the drywall up, cover the protrusion and put up shelves to disguise the odd looking space in your laundry room.

I would not recommend cutting 4in holes into a 5 1/2 wide pice of wood.

bonus if the floor is in an unfinished basement and can let the hosing hang from the floor joists.