Tom:
I have not fished down there in about 10-12 years, but years ago I did and there were some platforms off of Veracruz, to the N.East. Also out of Tecolutla and Tuxpan there were some platforms. There are also some seamounts and some neat bottom features scattered out in that area.
While not huge in numbers, there are some guys down there that do fish quite a bit. There was just a Marlin tournament in Veracruz. I am going to give you some links to a Mexican fishing forum that I read occasionally, and also some links on topics about fishing down there.
I know of a boat out of SPI that used to winter down in Campeche and Tabasco and had some real, real good fishing. It was the old "Pichora" a 50' Hatt.
When I fished down there I fished on a locals boat and basically helped them learn fishing. The big thing in that area is that it appears, at least it did to me, that the weather was better and seas much more fishable than up the coast. You might register and post a thread on this Mexican fishing forum and I bet you those guys will answer your questions and or help you out in anyway possible. The forum is all in Spanish so if you can get someone who speaks/reads it, it will be much easier. The forum is also complicated, but the section that you want is "Pesca de Altura", look for threads authored by a guy named Yusso.
Here is the main forum:
http://foros.pesca.org.mx/cgi-bin/Blah.pl?b-altura/s-30/
Here is a thread about Marlin fishing out of Tuxpan:
http://foros.pesca.org.mx/cgi-bin/Blah.pl?b-altura/m-1184170405/
Here is a thread about fishing the Campeche Banks:
http://foros.pesca.org.mx/cgi-bin/Blah.pl?b-altura/m-1183413234/
Here is a thread about the Veracruz Marlin tournament:
http://foros.pesca.org.mx/cgi-bin/Blah.pl?b-altura/m-1182790600/
Hope this helps.