I suggest that you keep pushing for the skip. It is low risk because as a mixed grade class room it is easy to undo. Ask for a 6 week trial and be willing to reevaluate at the end of the year. At the very least push for the 2nd grade math. My only concern is that in some schools the 2nd graders who get put in the combines group are the weaker students. Be sure you child is placed in the class with the strongest math students.
I'm not familar with rpi but with the IQ scores you are indicating a singlr skip iwould be expected to be very safe.
Educators seen to be more concerned that children feel succesful than that children learn that effort is part of learning. Keep reminding them that for your particular child the path to feeling succesful hass to involve overcoming some academic challenge.
Peace
Grinity
