Here is the text of the treaty:
Although it sounds like a good idea for a last resort, I don't think the treaty indicates Texas can secede. I think it says that we can form a total of four or five separate states. Can you imagine Texas having 8 or 10 Senators?
Sounds good to me!
Here is the pertinent text:
"New States of convenient size not exceeding four in number, in addition to said State of Texas and having sufficient population, may, hereafter by the consent of said State, be formed out of the territory thereof, which shall be entitled to admission under the provisions of the Federal Constitution."