Well, for starters, if you are going to use a prepared pie crust, get yourself the Pillsbury's that come two to a box and roll it out a little thinner and fit it into your own pie pan.
I make Lemon Merengue Pie with Lemon Curd for the filling, because it is so heavenly, so I use no conrstarch and no flour. and have no problem with "watery."
Betty, the fresh lemons have NOTHING to do with the "tinny" taste.
I have never used bottled lemon juice
and have never had any problem with tinny.