Tearing my hair out looking for a leak is exactly where I've been at for awhile now...
Your advice on using an infusion specific resin is spot on, but I'm going to jump on all the other details of your advice first in the hopes that if I get everything else right I can make use of the 30+ gallons of resin I already have and delay more hazmat shipping orders if at all possible.
(I have been degassing the epoxy in unmixed state and then metering out with a Michael Engineering Super E epoxy mixer with a static mixer as needed to the resin feed line bucket, so as to avoid excess exotherm or introduction of bubbles during the mixing process).
I perforated all the divinycell (by hand using finishing nails hammered into a piece of wood that I predrilled with narrower drill bit on a grid pattern, since I hadn't realized I was going to need perforated core at the time I bought it/availability in Hawai'i... I would be concerned with the holes becoming too small under vacuum since nails were pushed through vs drilling/cutting perforations except that my bottom skin has barely any, if any, dry spots but the top still has some dry spots even on my best attempts so far..).
What I've been infusing is actually quadaxial basalt as opposed to biaxial (weight 680 grams/sq. meter ie 19.9 oz./sq. yard with fiber orientation 0 degrees, 90 degrees, +45 degrees, -45 degrees and made with 13 micron roving), I'll try to get a good picture this evening in terms of the dry spots. Everything I've been making to date has been generally salvageable for non-critical applications a cabinet in a boat before I get things dialed in enough to do transom extensions and interior bulkheads but I'm running out of functional practice pieces so your advice comes at exactly the right time :-)
I can't say enough how much you've given me renewed hope dealing with resin infusions... :-)
David