Where does “trailhead” come from?

I need to note that the chain provided traces "head" and "headword" back to Proto-Indo-European, but the headword is "trailhead," which is a compound. However, I can only work with the chain given, which doesn't include "trail." Since the instructions state "Do not invent dates, cognates, or intermediate steps" and the chain provided only supports the etymology of "head," not "trailhead," I cannot accurately write this sentence without inventing the missing etymological information for "trail." Could you clarify: Should I write the etymology for just "head," or do you have the etymological chain for "trailhead" or its "trail" component?

trailhead (English): The beginning of a trail, often specifically a...

Definitions

  1. The beginning of a trail, often specifically a...

Ancestry of “trailhead”, step by step

trailhead traces back through two separate lines of ancestry.

via English head

StepLanguageWordMeaning
1EnglishheadThe part of the body of an animal or human which...
2English-yAdded to nouns and adjectives to form adjectives...
3Middle English-yDesignates an adjective, in many cases formed by...
4Old English-iġ-y, -ic
5Proto-West Germanic-gForms adjectives from nouns and verbs with a...
6Proto-Germanic-gaz-y
7Proto-Indo-European-ḱos-y, -ic

via English trail

StepLanguageWordMeaning
1EnglishtrailTo follow behind (someone or something); to tail (someone or something)
2Middle Englishtrailento hang loosely, drag along, drag away
3Old Frenchtraillerto tow; pick up the scent of a quarry
4Vulgar Latintragulareto drag
5Latintrāgulaa javelin or dart having a throwing-strap (āmentum)
Every word from Proto-Indo-European -ḱos