I do not think a DO is limited from doing an away rotation at an MD school, are they? I would HOPE they are not.
Many MD students do not have a home EM program. I did not; did 2 away rotations. I work at an academic center without EM and advise all my students to do at least one away rotation.
If you have *stellar* scores and class placement, you probably would still match without an academic program, but I still think you will be limiting yourself. Besides, I thought my away rotations were a TON of fun and I got to live somewhere new and exciting for a whole month and really eval the program and the living situation...