Hot glue does not make for a good sealant. Or at least one that will move the least little bit.
But I knew this. The glue around the power cord has since shrunk some and letting water out. Not a real biggie, as I didn't expect to be able to use the glue forever.
Going to try to silicone all the parts and pieces in this weekend, let it cure for a few days and start it on another test. So far, I'm still very pleased with this.