First off: Great name Barbie!
I was always under the impression that they wouldn't survive temps like that and we have similar winter weather as y'all. I have been tempted to find out for sure though. Problem is, I don't have enough big ones to "sacrifice" one in this way. ;)
Your El Capitalito survives? I always assumed it had the same temp requirements as other tropicals.
Barbie

The word "tropical" should tell you something. Tropicals will not survive freezing temps. They get damage at anything below 40 degrees. I'd suggest growing them in pots and moving them in in the winter, or using Rose of Sharon, which is hardy in your area.

Barbie, a number of tropicals (including Hibiscus rosa-sinensis cultivars) are long lasting along the Texas Gulf coast, but it depends on how close to the coast you are and your particular microclimate.

For example, according to the USDA my community is in zone 9a but the "official" reporting station is 8 miles further inland on a coastal prairie. We have more moderate weather than that station reports because of closer proximity to the Gulf and a "bottomland trees" ecology. Then add the mini microclimates around a property (south walls, under trees, etc) and that can push the zone to 10a cusp.

You might want to attend the Galveston County Master Gardener plant sale on 24 September, 9-3, at Clear Lake United Methodist Church 16335 El Camino Real in Clear Lake. You'll be able to talk to gardeners from your specific area and get their recommendations.