Autistic individuals with higher support needs, including those with co-occurring intellectual disability (ID) and language impairment (LI), are underrepresented in research. Researchers who attempt to include this population face unique challenges regarding participant recruitment, informed consent, accurate measurement, and protecting privacy and confidentiality. This leads to gaps in understanding as well as a lack of evidence-based support for clinical and public health practice. Careful consideration is needed to ensure that autism research is appropriately inclusive and does not unduly burden vulnerable populations. This commentary uses the Kass framework as an example scaffold for navigating complex ethical challenges and improving accessibility and fairness in autism research. It reviews existing literature on the topic, and the resulting recommendations are informed by autistic individuals with substantial support needs. Increased representation of the full autism spectrum in research is necessary to ensure equitable health outcomes for all autistic individuals. Ethical analysis, guidance from autism research organizations, and recommendations from autistic adults can assist with this process.