Y'all are fantastic, thank you for the advice! It's actually a 2006 S40 with 3800 miles on it (400 are mine), so the seat is probably broken in
but just not terribly friendly to my arse's geometry.
On the side I'm a private pilot experienced with risk management, so indeed, no passengers for a while - I'm taking that nice and slow. I actually bought the S40 against friend's recommendation for something bigger because I wanted to get my basic skills without struggling with a top-heavy monster. I was also compelled by the low-RPM performance of the S40 for urban, suburban and ex-burban driving, which is about 90% of what I'll use it for, though I would like to try a few 4-6 hour trips. I shelled out for a new multi-layer ballistic nylon body armored jacket and pants, a SNELL/DOT full-face white helmet, armored leather riding gloves and lightweight durable over-ankle boots. A little overkill perhaps, but I wanted to give myself extra protection while I get through the first 6-12 months of experience (I can shed the liners when it gets hot and still have the armor on). In July I'm taking the MSA basic rider's course and will have the full M endorsement at the end. I'll try to take the advanced course later in the year if there's an opening.
In the end, I figured that if I "lose" a few hundred bucks working my way up to a bigger bike, that's fine because it's cheaper than a single crash. I'm just surprised with how quickly I'm bonding with the bike and am wanting to spend more and more time on it, hence the riding comfort train of thought. Maybe someday I'd like to tow a passenger too.
Anyway, indeed I'll try the seat lift, then either forward controls or other seats to see if that helps before moving up with more experience and knowledge about what I really want to step up to. Sounds like a good plan to me, thanks for the influence!