> One question: If I end up having to solder parts onto both sides of the
> board, how do I keep the ones on the bottom from falling off? Are all SMT
> parts the same height, so that the oven tray will hold them in place until
> they cool off? Any suggestions are welcome.

Glue [or other similar adhesive].  Actually it's recommended for the parts
on both sides of the board, since otherwise parts might move slightly when
the board is put into or removed from the oven.