the google:
For flat work I made a frame press that will accommodate a 4x8 sheet; I would veneer the bottom of a table, and then veneer the top shortly afterwards on the same day. My vacuum pump runs constant and is set on a timer for 3 hours. I use Franklin Cold Press glue (similar to the Better Bond) and a much thinner caul (1/8" masonite); if the veneer is pourous I will place wax paper between the veneer and the caul, but I veneer directly without a crossband, so this would not be a problem for you in this application.
So far, this has not been an issue for me, and I have pressed a variety of veneers including burls, some that I have flattened myself.
Perhaps others will weigh in, but what jumps out at me is the thickness and rigidity of the cauls, as I think the idea is to draw the veneer down to the substrate, and the rigidity of 3/4" melamine might not pull down tight against the veneer, and unless everything makes contact everywhere, there will be areas that have no pressure applied to the veneer. This is also why I veneer one side at a time, as the rigidity of the substrate may replicate this condition on the bottom veneer as well, if you are veneering top and bottom in one pressing.
As I have no formal veneer training, but instead lots of trial and some error, others may well disagree with what I am saying, and weigh in with their view and experience.
Just trying to be helpful.
TonyF