Wow! Thanks for all the information everyone. There appears to be a lot of info out there; more than I thought there was. I don' t think my "fit" is way off, but since I have never been fitted by someone who knows what they're doing, there is probably a lot of room for improvement. I just turned sixty and, as a birthday present for myself, signed up to do the Markleeville "Death Ride." So any small tweaks I can do to make myself more efficient and/or more comfortable will be helpful! These suggestions and links are very much appreciated. Thanks, again.
For a ride like that, I'd recommend comfort as your highest priority. That probably means your saddle will wind up a bit lower and farther back than KOPS would tell you.
FWIW, I think the premise of KOPS is flawed - you don't see recumbent rider's knees exploding from pedaling a crankset that's above and in front of the knees. Does KOPS work? IMO, kinda. Just like all "fit systems" that use measurements, it gets you "kinda" right. Which is why I love that Peter White fit page - it explains what position changes actually DO instead of using psuedo-science to say "THIS is where you belong, damnit!!!".