My brother was playing last night and got the Eldin tower just so he could shield surf down the mountain from it and I wanted to try, so I switched to my profile and did some shield surfing, Guardian hunting and in general flexing on him.
So update: I didn't find that Lynel, I did find Grayson the Goron. Raid on the castle went rather well, I'm stocking up on food before grabbing some memories and then heading south, for real this time.
I got the MS and the shrine in the dark ruins just north of it, then I spent a while just living a peaceful life, got my Stasis rune upgraded, maxed out my house, worked on my Compendium, sold some stuff, did some cooking. Pretty relaxing on a rainy day.