Battery weight

I am looking for 40 pounds or less. I think I will go with a smaller less AH battery. I can paddle if it goes down. I use the trolling motor on the lowest speed to conserve battery power. We sometime float up to 30 miles per trip. Over half of that will not require a motor as the current takes you right along, but in the big holes of water with little or no current you have to paddle. I don't mind the paddling but it takes away from the fishing, thus the trolling motor. I may have to bite the bullet and get the Lithium Ion but $450 for a 10 pound 35AH battery is a little hard for me to grasp. Some of my friends have Yeti ice chests, I don't get that either. They just have more ice to take home than I do at the end of the trip.