I have already done this, so I will tell you what I did.
I went to walmart and got a size rubbermaid container that would fit the rays I wanted to put in there. Rubbermaid with a lid. (made sure its a deep container)
filled with 1/4 full.
didnt feed my rays for two days just before the trip. but a day will be ok to if you decided to do it this way.
I put a small hole just the size of a airtube in the lid. ran air tube thru it, and added a airstone to it. then put a regular airpump on the other end. I powered it with one of those converters that plug into your cigarette lighters and that then puts out 110v.
This way I didnt have to worry about batteries for my portable air pumps.
after putting the rays in, put lid on and duck tape around the edges to make for sure its water tight...
Moved 24 hrs away. We didnt drive straight thru. So after stopping over night, I opened the container and put about a gallon and a half of RO water in the container to just give some freshwater to them.
Had no problems. Didnt have to worry about batteries running low or anything and rays had plenty of room to move around without an problems.
If a ray can travel over here from were ever and be in a bag for 48 hrs. then sometime have to travel again in another bag for 24 hrs, then for your trip they will be fine. My biggest deal is you take more of a chance keeping them in a bag that they have less freshwater for the bio to get deluted in. Thats why I did the rubbermaid trip since they have more water to keep the ammonia and any bio less than what would be in a bag.
I transported rays, aro's, CK and angels this way. Every fish I had lived with no problems what so ever..