I dont know, its tough. The travelling time would concern me, but if you do some long 'practice runs' as you say that would be a good idea. If its only 3 hours as you say, I suppose someone could take her back home if it all goes wrong?
I know Evie would love a new place to explore, as she often accompanies me to my parents for Sunday lunch. She isnt bothered at all by being in a carrier or the car. However Denzel and Dexter would not like it at all....
Maybe you could take her to 'visit' a friend or another relative for a couple of hours to see how she copes in a totally new place?