Don't *****foot around your horse. Get a little bit sloppy with your movements and if she reacts with a jump, other than you taking care not to get stepped on, ignore her and keep moving normally. After a bit she will stop jumping.
The more you try t protect her from things that spook her, the less able she is to handle such things when they DO come along, unplanned.
So, yes, occasionally put up things that might be scary, just don't try to force her to go up to it . Just walk her by it, far enough away that she can see it, but not so she is panicked. YOU walk as if you havn't eve seen the scary thing. Focus PAST it, not at it. This will help you to be confident and draw her past the scary thing. Nexdt time go past it closer, again, don't look at it, look past it. Eventually , stop and stand near it as if you need to pick some daisys or scratch your nose and are just passin' the time of day, oblivious to the scary thing, Then if she wants to go jput her nose to it, let her.