I would really recommend Linda at Ireland Walk Bike Hike www.irelandwalkhikebike.com
She is local to the area and so knowledgeable, shares all the hidden gems and local insights and offers a great range of walks and hikes. She is super nice and professional and genuine in wanting you to have the best experience of her home locality. I would have no hesitation in recommending her for a really authentic experience.
I hope this helps!
PS: While you are in Dingle/Killarney you have got to try Murphy's brown bread ice-cream! It's incredible. I don't even love ice-cream that much but this is different...WOW! Their sundaes are honestly in a league of their own!