Hi Tom,
A few years ago I replumbed my galley thru-hull plumbing and took the ice box drain off the thru hull. It seemed like an unnecessary complication. The drain now runs to a simple hand pump and I pump into a galley pot when I need to drain the icebox. It seems like a safer/simpler set up.
In fairness, with a reefer I don't have to drain it very often, and your setup may well be a convenience you prefer to keep using ice blocks.
All the best,
Max