I have a Wolfman Mini Beta rear bag I have been using without a rack with zero issues. I think I posted pics of it already but if I didn't I will be glad to do so, just let me know. I also have the Wolfman Enduro tank bag...I never take it off. The Mini Beta hold my sleeping bag, one man tent, 3 changes of clothes, pillow, toiletries, cooking stuff, all with no problem. I ran into a guy on ktmtalk who fabbed me a bracket which mounts in the 2 holes that hold the exhaust onto the bike. This bracket keeps my bag and plastic off the pipe very well and only cost me a little money.
I have a Renazco seat being worked on this weekend so when it arrives I will post some pictures up for you. My bony butt could not last 15 minutes on the stocker.
A cush hub is a rubber dampenned wheel which would ease the stress on the drivetrain. Do a quick search, there is plenty of info on it. LC4 rear wheels are cush hub equipped and would fit, but are hard to find used at a decent price. Contact cmwoody with Woody's Wheel Works...he will make you one up. Also, I believe he was working on a billet cush hub for these bikes..not sure if that ever came to fruition or not.
Go with the Scotts damper as all the research I have been doing lately says it is the better one (I have no firsthand experience with this) as it has a high speed AND a low speed adjuster. As I understand it, Scotts owns the patent on this and all other dampers have only one setting.
Also, you are talking about wiring GPS into the bike...not sure of your other electrical plans but the stock stator cannot handle many additional items. To give you an idea: I have a Baja Designs kit installed, and I want heated grips and an 80/80 watt bulb. I am told I need at least a stator rewind. I am currently trying to determine exactly what needs to be done to get more power...I cannot seem to find a good straight answer on this. I am planning on calling Trail Tech Monday am to see what the experts have to say on the subject.
Oh yeah, I should mention that my oil cooler has been SOLD. Thanks!