If you went to school full time while getting a 525 MCAT and 3.6 GPA, you should be very competitive, especially for Dartmouth, which rewards nontrads and reinvention. There shouldn't be any question about your academic skills, and you have enough clinical experience to show you're committed to medicine. Hell, even if you didn't go to school full time while working, a 525/3.6 is nothing to sneeze at. Ask guys like @Goro for advice, but damn, you've got a decent chance at top 20s.
Yea I agree with the above poster, Dartmouth is notorious for putting a lot of stock into what non trads have accomplished to put an app together.
Don't be top heavy though. These forums are littered with applicants with great stats who applied all top 20 and didnt get in anywhere. The competition to get into a school of that caliber is absolutely ridiculous. Be smart and apply to "mid" tier schools too. We are talking about medical school here, after all. Pretty much all US schools are great and will get you where you want to go.
In order to be assured success at top 20s, you need to be an insane applicant, Lifetime-movie worthy. Here's a profile of someone who could very well get away with applying all top 20:
Patricia Tillman was born into grinding poverty in the hills of West Virginia. Her mother never knew where her father was, and at the age of three, her mother's meth addiction was too much for her, and she bounced from foster home to foster home. When she was 12, a track coach reached out to her, and she quickly became a star; although she only attended that high school for six months, the experience was enough for her to nurture a deep and abiding love for track. This eventually gave her a path out of her chaotic and often-painful existence, as coaches from several large universities offered her scholarships. She accepted an athletic scholarship to the University of West Virginia, earning a 4.0 GPA in chemistry while she was there, and winning a bronze medal at the Olympics in the heptathlon and silver in the 800 meters. She considered a career as a professional runner, but turned it down to enlist in the Army, becoming the first female combat medic to serve as an Army Ranger. After her time in the Army was over, she took the MCAT and earned a 526.
Girl from foster care becomes Olympic medalist and first female Ranger combat medic with 4.0/526; 100 hours of shadowing and 100 hours of tutoring at-risk children. This person IMO could easily apply top-20 only and have a stellar cycle; her ECs and stats are at least as good as William Hwang's, if not better.