The main thing you need to do with side lying issues is core strengthening. No offense and I am sure I will get jumped on for this but shoving Ibuprofen down your throat is going to do a couple of things. One it will screw up your stomach, 2 it only masks the issues. Hikers tend to use Ibuprofen in excess and it only leads to other issues and are so quick to offer it up as a suggestion when dealing with pain on the trail. Next, I would look at the suggestions here when using the various sleeping pads like the BA. Also maybe look at a hiker pillow like the roll up thermarest to help straighten your spine. Having those misalignments in your spine esp at your cervical region can lead to issue further down your spine. I would also throw in some stretching before your retire to your tent. Leading up to your hike, id look at getting some bodywork done, specifically either Deep Tissue or Trigger Point release or even better yet, Thai Massage. You would not believe the results you will get from having someone take an hour to stretch your body. The piriformis stretches alone are amazing. Good luck in finding what works for you, but do yourself a favor and lay off the Ibuprofen, or atleast, do it in moderation if you can. In case you are wondering, yes I am a massage therapist and cant tell you how many clients I have had in the past couple of months that have come to me with the exact problem you are outlining and have received multiple benefits from the work I do. Good luck finding what works for you