Trolling motor and batteries

I have a sticksteer boat and need to add another battery to my 12volt trolling motor,the only place I can find is under the back seat,only want to add a 24 size battery,would have to run about a 4FT jumper from the other battery,any suggestions or what to do.Thanks

Get some battery cables from your local auto parts store.

Do you see any problems with mounting the battery under the seat,the boxes are made of a hard plastic material

On my last boat I had to install one like that. Didn't have any problems.