For starters, the real castaway was only four years, making the decision easy.
Now, the little unspoken question mark here is, "What kind of hard time are we talking about?" If we're talking about a daily gang rape... gimme the 20 years on an island any day, thank you very much.
If you're talking about a cell, prison food, an occasional fight, TV, prison football and a weight room... well, that's just kinda like taking a year off of work. Hard time and Club Med kinda rolled into one and sure... gimme the year.