I believe this is the right perk (the one where you're the last remaining survivor so you get a boost to finishing remaining gens.)
Anyway, so as it seems less use than ever, I was thinking maybe something which could make it a perk worth using would be this: IF the killer slugs/hooks the 3rd survivor (last remaining other than yourself) then the perk activates at that point, so as the 4th/last remaining survivor in a position to actually do gens then they get the boost at that point which then allows them the chance to not only get gens done to enable the exit gates to be powered but ALSO gives the slugged survivor the chance of getting Adrenaline to get back up or to be given a decent chance if unhooked.
I don't feel this would be in any way unfair on the killer - once a killer slugs that 3rd survivor it currently leaves the remaining survivor with very little chance of escape, especially if the gates are within reach of each other.
I have to say, I'm very much NOT a fan of Adrenaline (boosted af), but the hatch mechanic in it's current state really rewards a slugging killer too much imo, especially when there may only be 3 gens done at that point, and seriously, when is the perk (Left Behind) EVER going to be getting ANY use now anyway? It's not like the stand-off is a thing any more, the hatch opens as soon as the 3rd surv is out of the game, killer closes it and it's EGC time, no gens able to be done.