I wonder if secession is the right move here. Many would argue that it is not permitted under the treaty that made Texas a state. However, there is a little known article of that treaty that permits Texas at any time to voluntarily break up into as many as five states. If the borders are drawn correctly we should be able to ensure that at least four of them are solid red. That would give us a net gain of two states’ worth of senators and most of the electoral votes.
The very act of seceding means that the state is no longer subject to those laws. "Legality" has no meaning when it comes to actual secession.