Hello!
If not, what base would you accept.
I instruct IFR in singles and twins. Our FTO has a requirement that the ceiling must be 500ft or more along the whole route. After a recent engine failure in one of our training aircraft (during the annual checkride of one of our instructors with an examiner!) I have raised this minimum to 1000ft. For me personally (or otherwise, triplicate my hourly rate...). Over water, I would probably accept 500ft, but certainly not less. In a twin I do not care too much, at least not during a training flight with only two or three occupants and no baggage. Even a Seminole can maintain 5000ft on one engine if it is not fully loaded.
Happy landings,
max