I try not to.
by "the border" do you mean the entire united states? It is the laws of the usa that dictate the laws at the border. Also, if the usa and the usa/mexican border, and the usa all decide to legalize marijuana so it can be traded as a commodity, doesn't your initial plan of making mexico into Amsterdam no longer make sense?
First off I also think Texas should secede and would be America's link to imported Marijuana. And I think Mexico has way more money, and ma power invested in Marijuana than Americans do. So, I believe if America legalized weed (and therefore stopped going into other countries to attack people for it), Texas would be it's flow for import, Mexico could develop its marijuana technology and MORE than compete with the American market, while Texas can tax it and it can make profit THROUGH the American market. There would still be issues at the border of illegal weed coming in, but there would be reasons for and plenty of hemp products, and raw cannabis that it would be a lot safer for the regular citizen in any single one of these countries.