Here is what it says in the USASF Rules:
"For Junior Co-Ed Levels 3, 4 and 5, if there is only ONE co-ed competing in a respective level, then that level must be combined into
one Junior division (i.e. Four Junior Level 3 teams and one Junior Co-Ed Level 3 team = 5 Junior Level 3 teams for competition). If the
Junior teams were split into Small and Large, then the Co-Ed team must be placed with the teams closest to its size.
For Senior Co-Ed Levels 3 and 4, if there is only ONE co-ed competing in a respective level, then that level must be combined into one
Senior division (i.e. Four Senior Level 3 teams and one Senior Co-Ed Level 3 team = Five Senior Level 3 teams for competition). If the
Senior teams were split into Small and Large, then the Co-Ed team must be placed with the teams closest to its size."
So the answer to your question would be yes. There would need to be two co-ed teams to have its own division.