On the lethality of wilderness encounters, it's valuable to note the section on Wilderness Evasion, which gives small parties of low level adventurers a fair shot at avoiding and escaping many encounters. Likewise, many monsters won't make their morale check to pursue, so together those let adventurers make it to the dungeon where you note they can find more consistently manageable threats.
On the lethality of wilderness encounters, it's valuable to note the section on Wilderness Evasion, which gives small parties of low level adventurers a fair shot at avoiding and escaping many encounters. Likewise, many monsters won't make their morale check to pursue, so together those let adventurers make it to the dungeon where you note they can find more consistently manageable threats.