That will work fine. They generally come with the u-bolts and backing plates for mounting. Definitely get the fender guards with adjustable footrests. Any passenger needs a place to brace their feet for safety and it's much easier on their back, even a 6 year old. The rear seat/box I have is very similar to that one, except it has a shelf with a strap for a 2-1/2 gallon gas can, or a cooler. You give up a little storage in the middle, but for me anyway it's worth it. It's awesome that you are going to take the little guy fishing, riding, etc. These will be the best of times for you. Good luck and have fun!Anyone used one of these? I want a seat and storage on the back of my Grizzly 350 for my 6 year old son for when's we go exploring, fishing etc. these look good but I am wondering how they go in real life??