detecting custom item use

what's the convention for detecting the player's desire to use a non-right clickable item, without the new 'everything is food' attribute?
i want to turn player heads into custom food. i thought there was a using_item trigger that would launch before the head was placed. i wanted the use function to be able to be used anywhere, facing empty air or sky. i didn't want to have to figure out how to delete blocks after they've been placed. but i do want the player to be able to place the block as normal when they shift.
what can i do to detect that a player wants to eat an item? shifting while holding doesn't work. looking down and selecting is weird. there's lots of cases where a player might be moving around and not want to trigger eating a custom item. the last suggestion i heard was "villager rides player with no trades, right click while holding player head" and that'd conflict with any other datapack using riding villagers and also be laggy.