O boy Jeff do I have something for you.
Forbidden Lands is a rpg that has everything you need to run a exploration campaign.
Easy resource management, exciting travel mechanics with interesting events that can happen, random tables for making towns/castles/dungeons.
The original setting is usable for your idea but it isn't hard to change it into whatever you want.
It even has a lsrge snd nice looking map with stickers you can use to show where you have explored!
I'm running a pbp of this game and is looking for players for a oneshot so if this sounds interesting you are welcome to join one of those to try the system out.
Here's a free trial version of the game: