I purchased a device from my local shell dealer that hangs from a rafter in
the garage, which has a hook at each of the 4 corners, designed to hook to
the bottom of a modern shell (the hooks are large, square shapes with plenty
of padding).  It's a little difficult to put on, or remove the hooks, but
fortunately, you only have to work with the weight of one corner at a time.
It has a winching system that requires very little effort to actually raise
of lower the shell.  So, I back in, and either hook up the shell and raise
it, or lower the shell and unhook it.  Precise positioning of the truck
under the winch isn't requred as it's easy to move it around (within a few
inches) while it's suspended from the lifting device.  I don't know the name
of the manufacturer, but it cost me about $200.  I can provide pictures if
you want.