I also suffer from illness-related PTSD. Water-Bug has given you some good advise. Knowing that you have the support services/meds close by can be very reassuring. And what Scott and and Gotsmart is very true. Once you spend a lot of time in the RV it does become a home away from home. Sometimes just facing the demons head on is the best medicine.
Have you determined what your triggers are? I know that isn't always possible, but with the help of a therapist you might be able to and do your best to avoid them. If they just "happen", there are other techniques you can try to calm yourself down that don't employ meds. Mediation, concentrated breathing and distraction are a few. It's taken a lot of hard work, but I'm now at the point that when I feel an attack coming on, I do concentrated breathing and can beat the attack (about 95% of the time now). Check with your primary care doc and see if there's a PTSD specialist/therapist that you can work with to help you get through.