I thought this may be of interest. This is one of the trams in Stuttgart:
They are ca.39m long, 3.7m high and 2.5m wide. As you can see, they are canary yellow, and have lights. Being rail-borne vehicles they tend to move fairly predictably. Trams have been a feature of the city for over a century.
You would not believe how frequently someone drives into one, or pulls out in front of them. As these trams are also about 59t empty, this tends to end badly for the car.
Now, if drivers frequently miss this, I'm not sure how making myself look like a radioactive teletubby will help.
I think the problem in this discussion is that we're all talking about subjective safety, and make our decisions depending on what we feel is safe. Personally I feel perfectly safe in normal clothes (which in my work means brown/green/black with a cloth hat (or an Akubra when I'm feeling
sartorially extravagant or it's raining). I also feel it's best to have constant lights front and back, whatever conditions I'm riding in. There are some roads I won't ride, and some I'll only ride on weekends.
I'm sure others with the same commute would make different decisions. Unfortunately all of us are working on our instincts because there's very little evidence one way or the other: it's subjective safety, not proven safety, and telling someone it's their own fault for being injured when they don't follow our rules isn't helping.