Oli, the biggest of my bulldogs is really only about 75 to 80lbs. I have a couple females that are right around 65 lbs.
I've been lookin for a hi-viz, even reflective vest, for my pointer. I have seen several I like including one that is neoprene. I really only need it for when we're on public state grounds so the crazies dont shoot my dog, or if she runs off and I cant recall her, so shes visible while shes runnin around.
I keep a small cow bell on her when we hunt too, and some folks do beacon lights or beeping strobes, or if you have the $$$, a gps collar.