I’ve been to busy to write a report, but we discovered an easy bushwhack up to Haystack from the Jack Rabbit trail. Here is the gpx file for the route we followed from the trail junction:
We walked about 1/3 of a mile northwest on the Jack Rabbit trail (to what appeared to be the high point on that section of the Jack Rabbit Trail) then we headed southwest to the summit of Haystack. We used a Garmin Etrex Vista to guide us to the summit from the Jack Rabbit trail.
No underbrush to speak of. It was an easy walk. We eventually found what looked to be a herd path that took us right to the summit. On the way there you’ll pass this large rock:
The entire bushwhack was just 8 tenths of a mile and about 400 feet of elevation gain. Had we taken the trail route (which can see from the sign would have been 2.1 miles) we would have descended 500 feet then climbed 900 feet to the summit.