Ironfish653

I think the problem you’re going to run into is that on a non-cargo bike, long chain stays go along with a laid-back (slack) seat post, so you can’t bring your load platform (crate) without running into the back of the seat. Ironically, you might be able to better position the rack on a bike with a more vertical (aggressive) seat post, even with shorter seat stays.
Cannondale did this with their 1980’s vintage ST bikes; road bike-style geometry, with a slightly extended chain stay, reportedly provided very good handling when loaded.

I know you don’t want to hear it, but if you want to have that pickup truck bed of a crate on the back of your bike without it hanging off behind the wheel, then a long tail is pretty much your only off-the-shelf solution.

prairiepedaler

I too had noticed that even though the chainstays are longer on a bike (like that Dutch cruiser mentioned), the seat tube angle impinges upon any sort of storage area benefit behind the seat and load over the axle so therefore we're no further ahead with that setup. Looking at those other commercial examples though in the links I don't feel as bad having the load positioned as it currently is on my ride. Not close to ideal but doable and has been successful thus far. I think that a sort of springy strut from the back end of the crate to the frame would help as would an additional strut attached from the pannier rack closest to the frame to the nearest seatstay point.