Everyone has to start somewhere, I don't see why as a post-bacc you would have problems finding research when you get into med school. I know a few med students who got into research during med school so no biggie.
You can probably find research fellowships, internships, or just volunteer (like the ole undergrad days). For the most part, med schools have some faculty that are doing research, therefore they are more than happy to have additional labor😉.
On the flipside you may find research time and research options to be a tad more limited. For example, if you have a desire to do humanities research, it may be more challenging than say doing clinical research.