Went for a two hour ride on my '88 today and my poor 77-year-old boney butt is still hurting. I see a lot of sprung bobber-style seats on eBay. Do those help with that problem? Any suggestions or recommendations? If you switch to one of those what do you do with the wiring and rectifier under the original seat?
I had similar issues with my Harleys - I was only good for an hour or so.  I tried a gel seat on one but didn't notice much improvement.  When I had a Gold Wing I could ride all day. But as I got older the weight of those bikes got to be too much.

I bought a genuine factory hardtail a couple weeks ago, and the springs were clearly inadequate for a person of my weight, so I've made it my business to learn enough about sprung solo seats to stay out of surgery.

The most important single characteristic of a spring is the Spring Rate, which is a force / unit deflection distance number.  Next comes total allowable deflection, which is a function of spring length.  One might think they want a lot of travel with a low spring rate, for a nice soft, compliant ride, but that's your whole body bouncing, which can affect things like throttle position, center of gravity, etc.  Also, a sprung saddle gives at least some amount of vagueness to lateral positioning, as well as vertical, and there can be some amount of wiggle, depending on the precision of the fits, and this can be disconcerting, if the seat moves sideways while trying to hold a corner.  Most stuff for "bobbers", is, in my opinion, sold mainly on looks, so I wouldn't expect tight tolerance precision fits in the hardware.

The old school hardtail Harleys had "pogo" seatposts, that allowed the front of the seat to move up and down as well as the rear, but this design has all but been eliminated, as far as I can tell.  The current seats all seem to be hinged at the front, and only the rear is sprung, better than nothing and a lot easier to control lateral movement on.

Another thing to consider, there's no damping in the seat suspension, it's just springs, so there may be some oscillation, and the greater the travel, the more chance for this.

The springs come in a few different styles, and there are different lengths, and different spring rates available.  I've seen a few machines that use mountain bike rear suspension components as spring elements.  Some of the higher end of these modern components, DO incorporate damping.

As for your LS650, When I got mine, I found that it was a spine wrecker initially.  But, the preload on the shocks had been set too low, and my weight, (I'm about 225lbs), was causing the shocks to bottom out over bumps.  I cranked up preload to the 4th position, and things got much more to my liking.  If you haven't tried adjusting preload, I'd fool with that before moving towards springs.  Also, consider purchasing higher quality, shocks, perhaps tailored to your weight.

The bike's factory rear suspension is much more sophisticated than a sprung saddle.  Saddle springs are largely an affectation, for "coolness", in my opinion.  They were relevant to fat tire bicycles and hard tail motorcycles, but not worth much now.  I'm only investigating because I want to actually RIDE this silly hardtail I bought a little.