This study investigates the impacts of a Research Experiences for Teachers (RET) program on rural STEM educators and reports teachers' perspectives on how these experiences influence classroom practices. The program of focus occurred at a mid-sized university in the upper Midwest from 2016-2019. Over this period, eleven rural secondary STEM teachers participated in the 6-week long summer program and various workshops and professional development activities. The teachers in the program were "solitary" STEM teachers, meaning they were the only teacher of their subject in the school building. In this qualitative research study, a thematic analysis approach was used to code and analyze transcripts of teacher-participant interviews. Results from this study demonstrate that the "solitary" rural teachers who participated in an engineering-focused RET showed an increased understanding of design-based learning, workforce skills (i.e., 21st century skills), and the engineering design process. Other findings include participants developing a deeper appreciation of teaching a growth mindset, valuing professional networks and supports, and flattening the power structure in the classroom to empower students to have more freedom, responsibility, and control over their design choices.