That would be cool for a 2 1/2ton trailer too (or any trailer for that matter)
Most light duty dump kits like Hefty Products or Pierce Wrecker are available for $600-$1,500 depending on rated capacity, but are limited to a 45° dump angle. Northern sells the same kits.
I can tell you from personal experience that when you order one, you will be playing phone tag with the manufacturer and Northern because they ship all of the items (300-400lbs.) loose in a cardboard box on a pallet. The box was in tatters. Almost all of the hinge and pivot pins were lost and needed to be shipped again (at no cost) from the manufacturer. I just finished a dump conversion of a 75' C-30 used Marina truck (30,000 orig. mile 350/SM465) using said kit and it works well but took one or two tries to get the mounting position right. If mounted in other than the "right" spot, dump angle is reduced. The instructions were pretty vague but overall it wasn't bad. The motor and pump is a Monarch brand and is not a "power down."
To all the Dumpers out there... what are your opinions on whether or not power down is necessary in a dump.