Absolutely. Not in the 200 pound range, but almost certainly in the 180-190 pound area. That's 20-30 pounds on Turpin, and the dudes at 168 are cutting even more.
Are you talking about current day or the 90's - the time period this thread is discussing? If you mean current day then I thought that, since Gatti vs Gamache, steps had been taken to prevent this sort of thing from happening.
Current day, and no they haven't seriously tried anything. I think Ryan Garcia cuts from like 160 or something.
How is it possible for a fighter to enter the ring two stone heavier than he was at the weigh-in the day before?
No clue about the science behind it, but it's possible. Some dudes have even posted their weight online and it's quite shocking.
20-30lbs increase is certainly not typical. I took a decent sample size from here - https://basementgymboxing.blogspot.com/2014/06/fight-night-boxing-weights-rehydration_22.html?m=1 - a while ago, and calculated the average increase was about 8% of body weight. So, c.12-13 lbs for a MW. Some outliers are extreme. I read that Gilberto Ramierz was 204lbs on the night vs Boesel. Crazy to think he spent most of his career at 168lbs - https://www.boxingnews24.com/2022/05/should-gilberto-ramirez-move-to-cruiserweight/