According to the SS1000/BB1500 page, "mileages in excess of 1,800 miles in less than 24 hours will not be published." 2,000 miles in 24 hours is an average of 83.33 miles per hour if you never stopped. (That's faster than the speed limit on all but a 40 mile stretch of road in the US) The IBA requires a fuel receipt every 350 miles, which means you're going to have 5 fuel stops at least during the ride. An average of a short 12 minutes per fuel stop puts you making the 2,000 miles in 23 hours of riding, averaging 87 mph. (Faster than the speed limit on every US road) When you then factor in the time it takes to get off the interstate and back on, and the bathroom break you are going to have to make at some point, you'd be riding at 90 mph or more for a full 24 hours. There are very few interstates in the US where 90 mph or more won't get the attention of law enforcement. In most of the US, 90+ runs a real risk of having your bike impounded, especially if you've been riding all day and look fatigued/drunk. There are no roads where 90 mph for 24 hours can be considered safe riding. 90 mph for two hours can be safe, but not 24 hours.
I'm not a safety Nazi but that's excessive, reckless, and endangers the lives of everyone around you. It isn't something to aspire to. It is something to be ashamed of. If you knock out a BBG, stop for the night. Your mind and body need a rest. No amount of coffee or other stimulants will actually refresh you. Long distance riding requires a lot of focus and sharp reflexes. You can condition yourself to go a little more, but fatigue will catch up to you no matter who you are. Nobody is immune to the effects of fatigue.
I can tell you from experience, finishing up an SS2K after a BBG the first day is easy as pie. Get a good night's sleep and don't worry about the clock at that point. I had time for a full night's rest (8+ hours), and a stop back at home for a nice home cooked meal, and to plan out the last 500 mile leg, and to unpack the bike, and I ran into some bad traffic on that leg and still finished with hours to spare. If you can make the BBG, you've got the SS2K in the bag.