This came up a few weeks back & has really worked rather well ever since. Indeed its become the norm @ my house.
Usually in games, photos are taken for either battle reports or what looks to be a rather cinematic shot, like this:
However as you can see in the background of that photo, there's a wall. Yes right up against the table. You see my game room isn't big enough to allow for us to walk all the way around the table, so on one side, determining TLoS has always been kindova pain in the ass. Usually the player being targeted has to kneel down & see if they can see the enemy gun that's trying to shoot them, that or whomever is shooting will come around the table to do the same. Games @ my house are fun & friendly, so this isn't really an issue. However recently Murl (who gets full credit here) instead just pulled out his cell phone, placed it behind his tank turret, and snapped a shot. Like this:
Actually this is Screech doing the same thing earlier this week, and a photoshoped version of the photo taken. As you can see, the camera idea works great! I would imagine that this would also work well in a tourney and prevent a lot of arguing from a situation in which the tables are set end-to-end (which I have seen several times).
Once again, technology saves the day!