some flight programs, like hospital wing in memphis, require all flight nurses to be EMT-basics. the program is only a semester, and EASY for nurses.
you might want to get certified in this while you are losing the weight.
also, if your hospital has a flight program, find out who the big cheese is(director of program, or head nurse of the flight team), and let them know you are there, and interested(that's what i've done)
i, too, am interested in becoming a CFRN, and have taken the appro. steps. just gotta(huff puff), lose the weight.....
a vast critical care background also helps.
lastly, you may want to consider ground transport. if nothing else, you get great experience, and if you still want flight, the DEFINITELY look at that.