(1) A nice, broken-in Corbin classic solo seat with driver backrest (driver backrest is hands-down the best thing I ever spent money on for the RK).
(2) Multiple foot positions
A. I removed the crash bar and installed the Kuryakn (sp?) Mark IV cruise pegs (they install on the same holes as the crash bar does). I can stretch my legs a little with my feet on the pegs. I can totally stretch out with the heels of my boots on the pegs.
B. I removed the heel shifter. Now I can put my toes on the back edge of the floorboards.
C. I have passenger PEGS, not floorboards. I fold them down and put my instep (front of ankle)on the pegs with my feet pointing straight down behind the pegs.
With the stock foot position, that gives me 5 different foot/leg positions. Move around often! Also, probably not the safest thing, but with 16" apes, Ican stand up on the passenger pegs and really get the blood and air flowing!
(3) Some might not like this, but...Spray some baby powder all inside your jeans. Spread it around well. Now put your jeans on sans underwear and ride all day. NICE!!!
(4) Make sure your bars are adjusted for you.The stock position is not where the bars have to be.Sometimes just a little rotation of the bars in the clamps will give you a whole new level of comfort. Rotate the levers/controls to fit your riding style as well.
(5)It'll surprise you how awell-placed water bottle that's within reach while in the saddle will keep you in the saddle a little longer.
That's all I got. Good luck on the Iron Butt!!