"I don't have a hope in hell of becoming a world
champion or a TdF winner"
Yep, not a hope.
If you were curious about how well you compare to your peers in actual amateur competition join a local cycling club, pin on a number and find out. Here's a good choice:
http://www.brightonmitre.co.uk/
Club racing can be great fun or a soul crushing humiliation, your choice.
"For anyone sensible position is about comfort as well as speed."
A profound revelation, although one that usually occurs after a few weeks cycling to everyone.
Here's GL on being fit by Guimard:
"I realized how much the difference the right position makes. Not only did I ride better but all the muscles in my body loosened up.
I never had lower back pain anymore....I was using the muscular force in my legs more efficiently."
"You can fit yourself to your bike with some common sense,
and a bit of knowledge about fitting principles over the years."
Since you have been riding a bicycle "seriously" for less than a year, as mentioned in your previous posts, you certainly didn't intend to imply that you had actually spent "years" on bike fitting? Perhaps you meant "weeks" instead.
One could save those unproductive intervening years to come common-sensing along bit by bit by researching and understanding any one of several well documented fitting systems, applying their proven methods and proceeding to adapt. Or make it up yourself in blinding flashes of dubious inspiration as you have previously posted in your "rules of thumb". Your choice yet again.
"what suited him is thus irrelevant"
Perhaps when he wrote "Greg LeMond's Complete Book of Bicycling" for the general cycling public that isn't what GL thought, silly fellow.
The book goes into considerable detail on how anyone can apply the Guimard/LeMond fitting system themselves should they care to read, understand and apply it. Once again, how far wrong could that be?
-Bandera