Forget the moral high ground, just play the game and check Hispanic. Affirmative action is what it is, its part of the process of giving opportunity and building diversity. If all the top schools did was use some slide-rule admission bar based on scores you would have the top schools all 70%+ Asian, 10% jewish, 5% white and remainder minority. Don’t believe that, just look at Stuyvesant or Bronx Science here in NYC for what test-only would achieve.
When I applied to school almost 30 years ago I checked off ‘white’ while I was 100% ‘minority’ - the reason was I did not want to be identified as a minority because I wanted to be mainstream. I was ignorant. Nevertheless I still got into ivies and top LACs. But for getting into the reach schools you want, just keep your head down and play the game. You are authentic 1/4 URM, so go for it, no regrets. Its the system. Play it and benefit from it. There is no ‘high ground’ in this respect.