Again, there is NO linkage on that shock. If the spring is too progressive, then change the spring. I can't see spending a couple of grand to make this something that it isn't. It's not a dirt bike (when has Ducati ever made one of those?), it's a sport tourer you can take on fire roads. Who needs six inches of travel for that? The latest Harley tourers get by with only two inches of rear travel, and they sure sell a lot of them.
OTOH, if Ducati didn't increase the spring and damping rates for the Low model, you would drag pegs etc. sooner. I would hope that they did. But the forks need work anyway, and there is plenty of preload adjustment at the rear.
Methinks that you might be asking in too many different places, Roadchick. I'd expect a suspension guy to try to sell you new suspenders...
And my offer of a test ride still stands. I don't weigh that much more than you.