I think I'm going to walk later this year

Since I decided I'd visit the States for only two reasons this year (PNC Bank debit card and driver's-license renewal), I thought it might be a good idea to do a trans-Korea walk later this year (around my usual time of early fall), then skip the walk next year. I'm impatient to do the Four Rivers trail one more time because, if I do it this year, it'll finally be my fifth time doing it. Besides, it's my favorite trail. A quick review of what I've done over the years:

2017: Four Rivers (1)
2018: went to the US and France, pre-pandemic; hiked the Sèvres route to Niort a few times
2019: Four Rivers (2)
2020: Four Rivers (3)
2021: east-coast trail (never again)
2022: Jeju and the final part of the Nakdong River trail
2023: Four Rivers (4)
2024: Nakdong River trail (split into two parts due to injury)

There's something psychologically significant about saying I've walked a certain trail five times. At some point, if I'm still able, I might return to the Nakdong River trail to do a "redemption" walk—without stopping for weeks to convalesce this time (which will mean planning better re: foot care to avoid stupid injuries). I really did enjoy doing the Nakdong last year from Busan to Andong, and if I bring along chemical hand-warmers the next time I do it, I won't be averse to doing it, once again, in late fall/early winter. The nice thing about that time, as opposed to the September/October time frame, is the general lack of rain as nature prepares for its deep slumber. But we'll see.

Meanwhile, the only other hikes I've been thinking of for future years are (1) the one across the middle of the peninsula suggested by commenter Paul (but I don't know exactly which route he's referring to), (2) a possible walk along the west coast (my boss thinks the west coast is a lot quieter and less built up than the east coast), and (3) the Geumgang bike trail, which is supposed to be part of the "four rivers" system, but which doesn't lie along the 633K Incheon-to-Busan Four Rivers route (unless I missed something; none of the maps in the certification centers ever showed a detour to the Geumgang path*). If anyone has any other path suggestions, especially ones that minimize contact with civilization, please let me know. (If your suggestions are bike routes, do consider that waypoints for walkers are closer together than waypoints for bikers. I can't walk 120 km a day.)

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*Let me clarify that: I think the Geumgang path does, in fact, touch on the main, 633K Four Rivers path, but it's basically a spur.  So if you're traveling from Incheon to Busan, you'd have to walk out west along that spur, then back again, before continuing on to Busan. If you're on a bike, I guess it's no big deal. But if you're a walker, the detour feels a bit like a waste of time unless you've got a lot of time to spare. I think the fourth river in the Four Rivers system is the Yeongsangang (Yeongsan River). I'd need to look at a map to see if/how it attaches to the main Incheon-Busan route (it looks utterly disconnected). Based on photos, the route itself looks quite charming, actually, and it's only 133K long. I might take a few days to do it, but I'll have to look closely at a map before figuring out the overnight stops.