I wish you all fun! I might wander up Loch Etive via Bonawe for a nighter on Saturday, always fancied it. Currently on a mountain bike build which i'll be using after April for longer distance trips since have no car at this moment. Yeah they're is two gates 1 just past the Quarry and another further along the track. Only ever seen a campervan up that track lol Best access would be from top of loch. All the best!!