If you have any pictures of things that might interfere like tank guards or other accessories they would be helpful to see.
As far as cutting the cost down goes we would definately go the mass production route, or at least the job shop route. I live about 1 mile from a shop with the waterjet that has very reasonable rates...basicaly I will determine the shapes needed to make the plate and then just create cad files and go from there. Cutting the shaped out is easy, Now I am working on finding someplace that will do the welding and any bends at a reasonable rate.
My intuition nearly makes up for my lack of good judgement.
Just installed my new trolling motor