We used to take the Rainbow Park shortcut at all levels but last year it had filled with gravel and we had to drag quite a way - use at your own risk.
And an added caveat about Hell's: Lucifer (the big round rock center right just below the entrance) is usually easily missed and usually not a risk for wraps. A smaller rock, center right and a little further down (with I call HRE rock, because there's often an HRE boat wrapped there when we go through) can be a nasty wrap at lower levels. It can be avoided either side, though tight at low levels, but you have to commit early and follow through. Look downstream and don't mistake Lucifer for the end of the rapid.