It sounds so easy, even AO could do it!
I remember seeing a Youtube video review on a 16 ft Tracker boat earlier this year when I was (re)visiting my boat options. . I think this is it: https://youtu.be/DvNHoPV8osk
If my memory serves, the guy mentions the challenges of mounting a second battery because the boat is not set up to have 2 trolling motor batteries. The space where the trolling motor is located is tight. That maybe the biggest challenge. I don't see how it is insurmountable though. If there is a will...
PS: I just viewed the video really quickly. About 9 minutes into it, the guy talks about the challenges of mounting 2 batteries on a tracker V16. The location of the battery is between two storage spaces. Its is confined and the shape of the bow is preventing is such that mounting two batteries easily. His fix was to push one battery all the way to one side and mount as second, smaller battery due to space constraints. Seems doable.