Installing a Light Bar

I just purchased an 855D. It has both a polyroof and a windshield. I would like to install an OPT-7 32" light bar, but I am puzzled about how or where this thing would actually mount. I want it up top so that tall grass doesn't block the light when I am checking cows at night. Does anyone having any advice on mounting this thing or a bracket system that would work for said purpose?

Thanks,