No way, at least as far as Navy goes. Barely anyone seems to qualify for HPSP because of grades/MCAT (NROTC is pretty taxing on time). They've had numerous open spots for HPSP for ROTC for many years (once again, for the Navy).
If you have a weak GPA (~3.00) and a shoddy MCAT (probably >27), the officers at the ROTC unit will probably not even let you apply for HPSP.
To the OP: I'm pretty sure there are some strict rules as to when you can wear your uniform. Our ROTC unit told us not to wear it unless instructed to do so because of the potential negative attention it could attract. Uniforms are supposed to be worn for military functions only or when you are representing something military related. Of course, you can still do it, but be ready for the potential consequences. I'm sure your ROTC unit won't mind, but even when I was in ROTC, I thought it was a bit showy to wear the uniform when not instructed. Believe me, the interviewers will know you were in ROTC if you listed it and you don't wear a uniform, and if they don't, bring it up. They love to hear about ROTC (except the former active duty doctors who are bitter and may get a bit combative with you).