That is a better plan except for one small detail. If the U.S. declares war on Mexico......they’ll immediately surrender and then demand we rebuild Mexico for them. Hows about:
3) If Mexico won’t take it; trade California to China in exchange for extinguishment of the outstanding U.S. treasury bonds owned by China AND a 10 year commitment they’ll do daily live Reality TV Show broadcasts from their forced labor camps!
At first I had reservations about giving China a pied à terre in North America, but upon reflection I realized that (1) they've already got one in contemporary California and (2) giving it to Mexico is the same as giving it to China and (3) the ChiComs would be no worse and would be more fiscally responsible than the decadent California Leftists.
If China won't take it--maybe we can give it to North Korea.
Or--here's an idea--maybe we could make a deal with Kim Jon Um (is that his name?): we give him the California Leftists (they'll go voluntarily since they think North Korea is the world's perfect place) in return for...
...uh......what can we give him to take them?