"Prepare your dog in such a manner that the work he is normally called upon to do under-whelms him, not overwhelms him." ~ Evan Graham
“People who say it cannot be done should not interrupt those who are doing it.”
― George Bernard Shaw
The Smartwork System for Retriever Training (link)
I was warned a long time ago by someone that their dog was spooked by the coverall arms flapping in the wind and therefore they avoided those kinds of stickmen. My personal view on that is that I'd probably get my dog used to these sorts of objects as something not to be afraid of. Of course, if I had a dog that really hated them, maybe I'd feel otherwise.
Our training group includes folks that have their own permanent stickmen and also use an extra coat and some sort of internal frame and we train on both. If you've got a good breeze I think you should be cognizant of them flapping in the wind and the effect it may produce. I've seen the extra coat and make shift internal frame set up on double water marks before to supplement a thrower at each station (ie a thrower in a white coat and now a shirt on a stand as well). I think the intent was to make it easier for the dogs to discern each station better and not go back to an area of an old fall. What ended up happening, or how I read it anyway, was that while the dogs were swimming toward a mark the other station would start flapping and confuse them and they would swim towards the one flapping and for some of the dogs that ended up being the station they had just come from. I'm only just beginning to learn the art of unintended consequences with this sport.
I sometimes use a white plastic fence post and carry some white plastic "walmart type" shopping bags. Hook the handles onto the clips built into the post. Works very well and 1 bags carries 50 extra. Little bit of wind and they work like a large balloon, add some sun light from behind and they glow, 2 bags per post for extra visibility. CHEAP and EASY