Many thanks for all the advice on this.
I now have a Rule pump, as like Nick said, this is for small amounts when pottering about, rather than being swamped, and also often at speeds which would not evacuate via the bungs/trunks etc
It's also been a great insight into the different views on trunk use, and expectations about how much water people expect to take in as a "real" ribber :o)
As ever, really helpful advice with a good dollop of humour too.
Best wishes and thanks