The hot glue method didn't end up preventing corrosion.
It occurs to me now that polyurethane spray foam would probably work 100% and, further, the per use material cost would be a lot cheaper than epoxy. If you clean out the nozel with acetone after each use, you don't have to use the entire can all at once. I've done that before, and I've found that the leftover stores quite well.
Of course, it also means your node will be quite well insulated, so you may need to account for that, or possibly monitor the radios temperature so that you don't overheat it.