Topband: 4 square on sidehill

[Lew Sayre]

I'm pondering putting up a 4 square. An early problem would be the effect of
having the bases of each element at a different elevation relative to each
other. The QTH is on the top of a ridge so the bottom of each element could
be as much as 10-20 feet different in elevation.  Would this seriously screw
up the efficiency of a 4 square? a little? a lot? I know that the radiation
into the hill will be hurt but what about the other directions? Ridge runs
about 330-150 deg.
    Just trying to reason this through a bit before putting serious wire
in/on the ground.
  Tnx for any facts, observations, educated estimates or just wild-ass
guesses.
     73 and I remain,
     Lew   W7EW/W7AT