About the supertuck: Of course there may have loomed a crash, but then riders crash on descends in all kinds of positions - well, that's exaggerated, but not only "tucked" - in fact in no crash any of us seems to remember, while there have been lots of descend-crashes. Who knows, maybe riders are even more careful in that position.
And if there was such a crash, it certainly would not involve many riders. It would happen to the rider who chose to do it. It's also not like it's giving an immense advantage so that riders who are not comfortable with it are coerced to do it. It's mostly a thing that makes a rider feel he's faster, might gain a few seconds. It makes riders more comfortable because they can choose what they do.
So where do the most and worst crashes happen, statistically? - obviously when high speed and a full, nervous peloton are combined. So in sprints first, but those are a base of cycling races. Then in the preparation of sprints, in the final 10k, especially, when roads are narrowed by (sudden) road furniture. I know it's harder and harder to avoid roundabouts in countries like France, but it would probably help to look less at which city is willing to pay how much for a final, and more at where a rather safe sprint preparation is possible. Put the finish line outside of the city in some more cases, when there are wider roads.
Less motos! Less cars! Clear the road as best as possible, sometimes it's not possible, but sometimes it looks like one could have made a bigger effort.
About the feed zones, I think that's really worth addressing. A lot of crashes happen there. Usually not the bad ones, because the tempo isn't high, but yeah, if I was responsible, I would look there very closely, too, because those bidons, bags that need to be controlled... well, I'm not sure the new rules are helping that much, but at least that's an AREA where things could be better.
Furthermore make rules as strict and clear as possible that are known to everybody about the conduct in sprints and the peloton in general and enforce punishments - not by estimation after something happened, but following clear rules. I'm thinking of Groenewegen, Moscon...
Don't choose routes that cannot be made safe.
Adress the barriers - now, that has been done. Well done. Let's hope it helps a bit, at least.
That's where crashes happen, every race. Dangerous looking positions on a bike don't account for one bad accident I can recall. I'm sure there are some, but they must be very, very rare compared to all other things, and these positions actually add something to a bike race, so one should think twice before banning them.
By the way, I like your list, Logic. Include wheelies while in a race, even when at the end of a time trial. Something might happen to the rider and I see young children as young as eight copying it all the time. Also: No chatting. Distracts the riders.
So, my rant's over. I won't say a word more.