Opinions desired - 12vdc/120vac power DIY project

[Madcitylunartic]

Greetings - I have a 22ft LS with two foward fishing seats. In each front corner are pre-wired battery spot. With one have a large round 4-pin female outlet. Here's what I want to do;
- install a 12 volt battery in each station
- wire them in parallel
- isolate them from main starter battery.
- use the existing plug cutout to both 1) charge the batteries with 120v shore power and 2) draw power when underway - I'd like both 120vac and 12vdc
- I'd use the power to charge devices, power music, fans, deck lights, air compressor, perhaps even a small refrigerator or powered cooler
Questions:
- 2 x 12v batteries - should I go lithium or traditional? How many amps... 100?
- then how to charge batteries in-place from shore using extension cord from dock...what is a good charging unit for maybe just overnight charging with setup/configuration ideas?
- power out: use an inverter that has a couple USB, 12v round (cigarette lighter) and couple 120v outlets. So suggestions on a smallish weather proof unit that will fit next to the battery in the compartment?

Anyone done something like this? Thoughts, recommendations and ideas appreciated

Pics below

 

[Remediation]

That plug is for a trolling motor, so getting extra plugs to wire something should be easy. I did wire a 1600 watt inverter to my battery and found out that was not enough power to run a blender which was a real bummer. We still had our "Hop, Skip and go Naked" adult beverages just not blended.

 

[Madcitylunartic]

Thank you for response!

Yeah... Blenders are a wattage beast.

 

[Bill N]

I know a guy that runs a small ice maker off of an inverter connected to starting battery with no issues.
I wouldn't recommend this when anchored unless you have a backup battery for re-starting.