Just bought an XLT with the tow package, but we did NOT get the air leveling suspension....and we did not check it with our horse trailer until after we bought. We love the Expy, but I need to get the back-end level - what to do?

1) I have not found any aftermarket kits (yet)....anyone know of anything?
2) Is it possible to install the ford parts after-the-fact?

Thanks for any help/advice!

Tom C