A good read, thanks.
The interaction of enjoying the ride, pushing yourself, an external deadline etc etc is an interesting topic. It's not often talked about; most internet posts are either fist-punching macho competitive stuff, or "I wasnt rushing, just enjoying the scenery". You'd think there was nothing in between!
Even the audaxers mostly play down the challenge/achievement in a typically British way (usually a good thing - we don't want to get too American, do we?? ).
For me the best riding experiences have been where the mix ends up just right. You certainly cant predict when that will happen, nor control it. Also, I think "long distance" rides - and your 20hours definitely qualifies IMO - always involve mood swings. That can mean your mood needle swinging back-and-forth past the sweet-spot several times in the same ride. It's not always due to setbacks, or successes, or the weather/terrain/views - I think often it's just our brain messing with us. Part of the joy is that when you have a low-spot you know there is usually time for the needle to swing back. In a 10mile timetrial, once you start hating it that is probably how you will finish!
(I'm in danger of rambling on for longer than you did, and I haven't ridden anywhere so I better stop now.)
p.s. do you have a good shot of your fully-laden bike, showing the luggage properly? Your kit-list is interesting, I'd like to see how much space that really takes up.