Always better safe than sorry. Use a box. Go quick to a heated and warmed up car. Insulate the box with newspaper or something. Towels or rags. The dark is no issue. I mail them from florida to California. I think your southeast may be an improvement over your southwest solar exposure. Don't take the northeast.

I agree with Shavedmonkey. You will have better light for those orchids.

The biggest cause of bud drop/blast would be sudden changes in temps. Not so much the trip in the car as the heat/cold in the new apartment.

I moved from NYC to Florida. I took about 40 orchids along for the ride. It was September so the weather was moderate. All the plants did fine and most winter bloomers continued spiking and flowering in Dec/Jan.

Buds are different. Those buds are more sensitive than the plants.

This is what I did. Put all my orchids (except plants which were too big) in Styrofoam coolers. Buy the big, cheap ones. I didn't put the tops on, just piled the plants in. Put them in the car as the last trip to the new place. If the weather is really cold, just cover them with a blanket when you put them in and take them out. Get them in the new digs fast.

Don't put them close to the window. They don't need sun now. The buds are formed and the plants will do fine without strong light. Put them close together for some humidity and keep your fingers crossed. But, don't put them in direct light. Keep them back from the windows. Very important. The plants should continue along and bloom.

Good luck in your new place. The lighting sounds wonderful for orchids!

Jane