Go to a sams and buy a duracell group 24 deep cycle marine battery. About a hundred bucks. Made by East Penn, who also makes Deka batteries. MANY of us bass boaters use these (usually 2 or 3) for our trolling motors. Or go to O'Reillys and buy one of their store brand marine batteries. Made by exactly the same company with exactly the same specs. About the same price. Group 27 batteries get heavy, approaching 75 pounds for good ones. And group 31's are even better but also heavier. I'd stick with a group 24 in that kind of usage myself.
Also buy a good MARINE deep cycle battery charger. All chargers are not created equal. If you are close to a Bass Pro, Cabellas, etc, you can find lots of good choices that will charge this kind of battery as it needs to be charged. We typically see 4-5 years of service using a pair of group 27's 3 times a week on average.
2018 Tiffin Allegro 32SA