Surprisingly enough, my sealant and duct tape patch is holding. The car is leaking, but from the expansion tank, which is where it should. The automotive duct tape I used is turning out to be a surprise, and I believe I will make it to Friday/Saturday with no significant problems.
This raises a new question: Can you over-fill your coolant system? I (literally) topped off with water and assume the leakage is excess being kicked out.