When you say keep it simple it depends on what your wants and needs are on a longer trip.
This is what I do on Baja trips and longer trips to the river, I keep it simple.
I run a go-pro and a small fish finder for 10 days, and them turn off water and sleep periods. That's simple enough for a small automotive battery (225CCA) to handle. This will cost about $32-$36. Just fully charge it before each trip and your all set. (weight 36 lbs)
If your idea of simple includes laptops, cellphones, tablets, and large powerful sonar systems, it does gets more complicated and expensive.
I have no experience to help you there.
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