I installed both Hellwig bars on my 2009 standard length Limited, non-air spring model several years back. I recall the rear bar being a bit tight on the bushings but not as much as you described.
Only problem I've had with them is the grease/lube on the front bar dries out and it develops a squeak and some stiction effect, so requires re-greasing every 6-9 months or so. I bought zerks but never got around to drilling and tapping the bracket for them.
May be upgrading to a 2018 Max model soon so interested if the bars fit the newest models, despite the platform upgrade. The Hellwig website seems to imply they do.