Disable post lighting, or change the arena to night time while working with the offline target.
I've been building a terrain for offline use that when you click on a fighter spawn, your fighter is sitting on a hard stand leveled to test your convergence out to maximum range. Some fighters through the gunsight don't have shilo's problem while some do. So my solution was to turn of post lighting or even change the arena time to night time which is the best to see impacts on the target.
I've also set it up for the B25H and A20G. I still have a few fighters left to do, it is mind numbingly time consuming the steps to go through to tweak the ground under the fighter spawn to cause a fighter to sit with it's engine datum line leveled on it. I have 6 available spawn directions on a small airfield and am on my third airfield setting spawns because of the broad variations in length of landing gear.