Safe travels home.
The holding tanks are a bit too high to be useful and I'm not too keen on T-ing into the toilet thru hulls/risers, although as you say it would work with a gravity feed. I started investigating and checking my bilge alarm sensor and discovered that the alarm buzzer is not working and while I was mucking around the red light gave up the ghost too. Now looking for replacements for those.
My main way forward at the moment is to hook up the bilge high-water alarm sensor to my CerboGX system which is on-line all the time. This allows me to know if a highwater alarm occurs (if my bilge pump fails) and then get something done about it. Given its just a dehumidifier filling the bilge, nothing happens too quickly that I cant respond and get someone on board. That's the theory at least!