Thanks a lot guys. To answer your questions.
Dave - single battery system. I have a dashboard yes but was leaning towards just incorporating a switch near the battery rather than a dash. Obviously this won’t be as good as having it dash mounted though but that’s ok.
Raging - I was going to get a rule 500gph bilge pump. Or 750. The comments re Johnson pumps on this forum seem to suggest they give up a bit too early. I’ve seen a lot of people say add a fuse. Dumb qn but how do I do this (I’ve never done any electrics before so I’m just having a crack)
jon - enough for a days fishing roughly. So a dozen tanka’s, slimes, squid etc. I was going to use a 60l plastic barrel 3/4 full. The bilge pump will pump fresh water into the barrel and the overflow outlets will take out the old water. That’s my plan
xheers for your help