Check out this thread -
lots of nice rigs. Posts 13 and 151 have tongue mounted leaf loaders. In post 160, one of the guys shows a drawing of his box before he built it, but that is probably not what you are looking for.
I was looking for a thread that a guy made showing in detail how he built his trailer box with a tongue mount but didn't find it. Search in landscape maintenance, you'll find it. he ended up not using it much, so he says, and had it up for sale here very recently. It must have sold, i guess, because it's not in the classifieds anymore. I am wondering if he was having some of the same axle overload problems that a previous post here mentions, so he decided to sell it ? He says he didn't use it as much as he thought, but I would be careful about a tongue mount. Lots of effective setups can be found, but few are tongue mounts. Good luck !
PS I spent many years landscaping in Amherst and Clarence back in the 80's and 90's. Are things still hoppin" around there ?Go Bills !