200 amp alt for sure and for the GP3000 at least 1 good group 31 battery two would be better and for 7kd 200 amp alt and at least two good group 31 batteries 3 would be better. Suggestions for batteries something with over 100ah and over 1000cca. Kinetik 2400, NSB G3100, PM D3100, odyssey 2150's and there are some cheaper off brand batteries that you can find out there too.how much more electrical we talking about ? would just 200+ and the big 3 and 2 extra batt work ?