You are underestimating the impact of being in SHPEP. Many admissions committees understand why SHPEP exists and highly values individuals who benefit from the mentoring and community that SHPEP provides. It won't help you overcome a bad academic record, but it will give you insights about why healthcare needs those from underserved backgrounds in the workforce. You can always do research another summer, but SHPEP is only involved for those in their first two years of undergrad/community college.