The easiest 2 places are in the raw water pickup hose under/near the oil filter or right near the pickup in the floor.
I installed a raw water strainer near the oil filter location since it had the most room. My local Mastercraft dealership put an in-line garden hose fitting about 18-inches or so upstream from the hull pickup point. To get to it I just remove my center seat cushion and pull the fiberglass bin out and there it is.
If you've got a West Marine nearby they'll have the garden hose fitting. Just check the diameter of your raw water hose before you go. Should say right on the hose in blue or white lettering. I've got the LTR engine like yours. I think it's 1.25-inch, but I did it last year and my memory is fuzzy.