Re: "Hiking for Biking"
_Heck, if there's a better way to actively stretch out properly warmed-up legs that is not watching-paint-dry-boring I'd love to hear about it. _
I'm a big fan of the hike-a-bike-centric ride for expanding the adventure/exploration/uncommon terrain possibilities... but if you're purely looking for mobility, what about doing a quick circuit at the top of a climb targeting some of the muscle groups that you're hoping to stretch out? I'm no PT, but maybe some jumping/lunging, a deep squat or two... something that would open up the posterior chain and activate your calves to absorb and stay pliable in big compression moves.
I remember seeing a video (maybe with Curtis Keene or some such pro athlete) many years ago talking about training for the then-new discipline of 'enduro,' in which they were preaching the benefits of doing some strength activation with resistance bands at the top of a climb before dropping in.
Re: hiking as a form of "seeing lines" -- any (every) time I hike or run on a trail that I usually ride, it's like there are several alternate lines which I've never rode before that are suddenly glaringly obvious. Slowing things down to foot-speed is different enough that it's almost like coming to the trail for the first time again.
(Unrelated: am I the only one who feels like the gravel riding community is picking up with hike-a-bike-mandatory rides where the focused-on-designated-climb-trails mountain bikers may have left off?)