When you get your mortars, place the HQ unit in the second story. Make sure the mortars are deployed. Click on the HQ unit and select the artillery tab. Try aiming a little more to the right of where you are trying to get LOS in your picture. Aim for the cross road and see if that works for you. I was able to hit the cross road from that position with my HQ and mortars. You might not have LOS on the left side because of some of those tall trees in the bocage.