@Adam1784 I'm the sort of person who will backpack into a rustic cabin and enjoy the hell out of it. Walking 500 feet would not be a problem at all. You simply have to be absolutely clear about what to expect at your listing: the walk down the path, along with everything else.
There are tons of outdoorsy people for whom a 500 foot walk, up or down, wouldn't be a problem. Could you keep some large back-pack style baskets or bags in the parking area for guests to use? Not a real backpack, but something large with an open top, so folks could simply throw things inside and carry them (relatively) easily down the path? Same for bringing things back up? They make large drybags for river running/rafting that might work.
Obviously, you would have your place well outfitted, so guests would only have to bring their clothes and food. And you could certainly keep cooking basics in your listing so they don't have to bring cooking oil, etc.
The thing about STRs is simply to be absolutely clear about what you're offering, so there are no surprises.
If you build it, they will come. I don't know how old you are, but that's a reference to Field of Dreams, a movie that Kevin Costner was in. Anyway, good luck. Sounds amazing.