Just my two cents on this thread............just a mish-mash of 'stuff':
Preparing for touring gets easier the more you do it I have found. You learn to weed out what it is you don't really need - and generaly replace them with something that - oops - you maybe forgot the previous trip. Making a bike trip checklist is handy for this - we keep ours on the laptop so that we can edit it at any time.
Being tall (6') and a former athlete who now has low back/hip problems (nothing serious, just over did it when I was younger), I have a stretching routine I perform daily before I first get on the bike - a little stretching goes a long way when it comes to reducing any joint irritation or stiffness during the day. I pay special attention to my hip flexors (front of the hips) and make sure they are well stretched because those are the muscles that stay "flexed" all day when riding a bike (same as sitting in an office chair). Gets the blood flowing, clears my head and really does make me feel more loose.
I find that stopping every 200km (150 miles?) or so works best - for me I have no choice as at that point I have to get gas, too - as my tank is fairly small (hence the reason for selling the Meanie). A quick stretch, swig of water, snack and a yak during these breaks keeps me going all day long!
I travel most often with my husband - and we sometimes take our trailer (which he pulls with the Valkyrie) - so in those cases, I don't have to worry about "space" for stuff - we even take along the lawn chairs so we can sit and relax and have lunch at a rest area.
When I travel on my own for any distance, I feel the most important thing to have along is a (charged) cell phone. Second is a small (but well stocked) first aid kit. The cell phone I keep zipped in my jacket which in the case of an emergency I hope would stay with my body - it's useless in a saddlebag IMO.
There are things I keep handy in a little windsheild bag so I don't have to rustle through my saddlebags at every stop - these items are: air guage, sunscreen, lip balm, a spare contact lens, small camera, etc.
***CENSORED FOR LADIES ONLY*** - this is an idea my sister in law (who rides pilion) suggested for those really long trips - using pantiliners daily to reduce the pairs of underwear you may have to take along. I have never tried this myself, but it could be viable in certain situations. IMO if I have to pack THAT lightly, I'd find myself a new bike!
One last thing and that's about the sheepskin - I thought my husband (who's had many more years in the saddle than I) was nuts - sheepskin? Looks goofy, gotta be really hot, etc.....well, it's NOT. It will keep you cool when it's hot and warm when it's cool. It breathes and keeps you comfortable - even if you already have a comfy seat. Make sure you get real sheepskin - and you can get them in a variety of colors (I have lime green)....cut it to size, and away you go. Sheepskin can also be washed (not dried) with mild detergent to bring back it's "fluffiness".
Happy riding - I won't be going on any long rides now until the spring!!
I have to admit that I did not. So, on these past few trips I thought I did give it a try. At stop lights, I'll stand up or stretch out the neck muscles. While riding, I'll check my posture, are my elbows tucked in, shoulders and hand grip relaxed. Also it helps to be observant for any little aches that happen after even my short rides. I noticed that my right knee feels a bit stiff at times, so I'm focusing now on how the lower half of me sits on the bike. As far as stretching before I head out, again I have to admit that I don't because I just want to get out there and ride!
next year and was looking for info 
and want to be aware of.