I'm not following your numbers. 6 days for 3 adults on standard dining plan is $1359, 6 days park hoppers from
undercover tourist at the cheapest time of the year is $1470. That leaves $1871 for the room, or $277/night before taxes. The numbers could work if traveling at very least busy time of the year with the cheapest tickets and cheapest rates, but most people do not have that flexibility. And the numbers still seem low.
And I'd also love to see where 12% return is conservative and consistent. You could sell your advice and make a killing and have even more cash. It doesn't even need to be accurate, just need to be plausible enough to sell enough books.