I am rigging up the duck boat to do some angling. Yes I know i am running late. The boat will have a elec trolling motor, depth finder, and electric start 20horse. My questions are these for you who have far more knowledge than me. Do i run 2 DC batteries together in parallel for all or one for trolling motor one for starting motor/sonar? Anyone recommend a charging/tender system for the above scenario? thanks in advance anything else i need to know?