Welcome 007!
Keep an eye out for a white ST1300 out your way avid is a member here (Strider20?) . Can be seen on regular Sunday rides over Glorious, Kilcoy, Woodford and back to Samford.
John Moorehouse and his brother both modify seats. John gets you to sit on your existing seat and takes some photos and then modifies teh seat to suit your bum. the only drawback is you have to leave it with him for a couple of days.
Like you I ride all weather so I haven;t had teh opportunity to do that with this bike.
Some people swear by Sheepskin Seat covers, others by Air Hawk pads and some others recommend Gel seat pads.
A colleague who rides a lot of long distances recommended to me during the week not to wear ordinary jocks with the seam under the crease betwen bum and leg. He recommends boxers with stretch materials that don't have seams that go across you backside/legs.
Hope that helps.