Targetless does indeed allow the trooper to target a point on the ground, even in ARO. So it goes like this: 1. Active trooper Angus declares Move and moves. He sees reactive troopers Renee and Renaldo during his movement. 2. Renee declares BS Attack with smoke, and designates a point on the table for the smoke. We then place the smoke template, centered on the target point. Renaldo declares Dodge. 3. Angus declares BS Attack, splitting his burst between Renee and Renaldo. He also declares at what point on his movement path he will shoot from. Now, in Resolution we trace the path from Angus' shooting point to Renee. If that path goes through the smoke template, then Angus' shots against Renee will be f2f against her smoke shot. However, if the path doesn't go through the smoke, then they will each make normal rolls (not f2f). It doesn't matter whether the path between Angus and Renaldo goes through the smoke, because the smoke has nothing to do with Renaldo. Angus' shot at Renaldo will be f2f against Renaldo's Dodge, but won't be affected by Renee's smoke.
At the risk of derailing this too much from the original topic... it seems like throwing a smoke grenade is always better than a dodge if your main goal is simply not to be hit, yes? Because you can always throw it close enough to yourself to get a +3 to your PH roll... I presume you can also throw smoke as a ZoC-triggered ARO, which means you'd potentially avoid the -3 MOD for needing to dodge without LoF if someone is coming up on you and trying to shoot you from behind by smoking instead(?)
Yes, unless there are reasons not to want smoke in that spot. For example, your opponent might have another model nearby with MSV2 who will just shoot you through the smoke if you land it. Also, some troopers have smoke grenade launchers which will usually be worse odds than Dodge, and don't have hand-thrown smoke grenades. This one deserves its own thread. I will post it in a sec.
