Re: Tips on leaving boat in water all summer.
Paint the bottom with the correct antifouling paint for your environment (ask your marina). Also ask about which "zincs" to use.
Are you leaving the trailer there? If so, arrange in advance for someone to pull it out for you if there is a hurricane.
Get your mooring line instructions from someone at the marina, if you are at one, or from a neighbor if this is at a home.
Be sure the pump, float switch and discharge is working; test it with water, not by sound. haev a battery switch so you can shut off all power except the direct line to the bilge pump/float switch.
If you are at a marina, exchange phone numbers with neighbors to keep an eye on things, unless marina staff is on top of things. Some are, some aren't.
If you check on it and run it every other week your battery should be fine for your bilge pump. i don't think double batteries, shore power, trickle or solar chargers, are necessary and i think leaving a boat plugged in to shore power risks too much eletrolysis.