What happens if I am flying at a higher Lift/Drag ratio than required?
If your optimal lift coefficient for long range cruise flight is greater than what you need, you are flying too fast, or too low.
For cruise flight, your lift needs to equal the weight, otherwise the aircraft will accelerate upwards (in the body frame of reference).
If you know the lift coefficient that is optimal for cruise, you need to adjust the airspeed and density (altitude) to make sure that the resulting lift equals the weight.
$W = L = \frac{1}{2}\rho V^2 C_L S $
$\rho V^2 = \frac{2 W}{C_LS}$
Reduce speed and/or increase altitude until the lift and weight are equal at the optimal lift coefficient. That will give you the maximum range.