WalMart series 27 is all you need for the Pelican. They will last a long time between charges. I fish all day
in my Pelican with a 27 series with a 30# MinnKota and it still shows 12volts. Don't take much to pull that Pelican around. I used a lawn mower battery for a long time. Would last 5-6 hours.
Those golf cart batteries would last forever in that Pelican, BUT, they weigh as much as the boat.
Whatever you get, check the water level regularly and charge as soon as possible after use. If it's in your budget use a 5amp, three stage charger. They are temperature sensing and will only supply juice when the battery needs it. A 2 amp trickle charger provides 2amps all the time.