Shoot, Santa - just keep her riding and keep urging her to increase what she can do for a year, then reevaluate the trip.

In a year, odds are good she'll be either hardcore and wanting to do it, or she'll have gone off into some other interest, like almost every other body that takes up riding as an adult. A year of South Texas riding will seperate the chaff from the wheat.

If she still wants it, go out and make that long ride your b!tch. If not, do something else, no foul. It may be a death march in the end anyway, but it won't be a failure unless you don't go. The difference between and ordeal and an adventure is only a couple of weeks and a few retellings of the story.

For the record, I've ridden from DFW to Corpus Christi a couple times and figured out it was the wrong direction to go. At least you'll have some nice tailwinds for the ride.