While a graphing, and in fact CAS calculator, the HP Prime has a feature where you can disable various parts of the calculator for a pre-determined amount of time. I believe you can disable various applications, and the CAS functionality to give you purely a scientific RPN, Ti style algebraic, or what HP calls Textbook entry. It will also blink lights at the top of the device to show it's in that mode. It's backlit, rechargable, and has uses well into college. If you intend to instruct this class, and are looking to give it to a specific student, it could be a very viable option.
It is 100-130USD depending on where you pick it up and when, so it's possibly not an amazing option.
I haven't seem many backlit scientific only calculators, and I am assuming if you haven't found on on the google machine, they likely don't exist in the specification you require. Options could include getting a cheap calculator that meets your requirements and slapping a frontlight in it, finding a rare and likely collectible LED based calculator (they haven't been made since the 1970's I wouldn't think), or look to see if someone has an open source calculator already designed, which which you can swap out the screen for something like a compatible OLED display or backlit LCD, and disable whatever features you wouldn't want in software.