I have traveled a lot by plane and car with rsd. Actually more then when I didn't have it. Is your husband going to do the driving? I hope so because that will help. It is key and I mean this to get out every few hours and move. Even if you don't feel you need to because I found for myself if I don't and I allow myself to get too stiffed and cramp and then get out it is too late so to speak and the pain has gotten to bad. I would bring meds,where comfy clothing,eat and drink in a proper way. How far of a drive is it? If it is real long I would stop and stay in a hotel so that you can get full rest. On a side note is there anyway you can fly and your husband could meet you there? I hope your sister takes care. That is so wonderful of you to want to be there for her. Many thought to you and your family