Yes, cruel and a lot of traveling. I'm not looking forward to that. It would have been nice if instead of another huge loop that Drakebreath City was somewhere close to Yellow Town accessible via a late-received HM in the game, or one only useable after defeating the last Gym before the Tablet Trek. Perhaps another long Route could have been in between the two. (But seriously, come on - why can't we at least receive Fly by the 8th Gym instead of in the post-game? Why was there no HM-removable blocker on 417 instead to shorten the trek, with HM received in Drakebreathe or sometime after Snowce City? Just these little things could have been improvements...)
And while I'm at it, I'm now looking at the map. Where on Earth is Route 503? I don't even see data for it.
Did you already got HM2? If not, you can get it in one 0f the house in Serenity City.