Since it's 'clothing' you'll be ok with that, try to use an opportunity to put it on and remove it that isn't going to slow things down for your group though. So maybe put the jacket on while you're waiting for your turn.
Generally speaking ( not directed at you
As with all things FT, the rules are boundaries so there are loopholes in them (deliberately) but that isn't an invitation to see how far you can push those boundaries.
If it gets to the point where people are bringing a full change of clothes with them including target trousers, boots etc etc.. that's obviously pushing it waaaay too far. If it's a case of just putting on and taking off your jacket, that seems perfectly reasonable to me.
If someone starts going round with 3 jackets - one for standing, one for kneeling, one for sitting etc - that's obviously not going to be ok.
Be sensible, reasonable and sportsmanlike and you'll be ok - start looking for loopholes and seeing how far you can exploit them and it might cost you targets.