16MHz Crystal with 2p load capacity: What load capacitors are necessary
Don't rely on parasitic capacitance.  Put the two capacitors in there and you can adjust them later if you need to.  You won't be able to probe the crystal directly because it's parasitic capacitance usually kills high Q resonators.  You can however tell if the processor is running when configured for the external crystal oscillator.

Once you have the processor running drive an I/O line up and down to an LED (once a second or something) to watch for any failures in the oscillator.  Hit it with some cold spray and see if it dies.  Likewise heat it up to see if it dies.  That will give you an idea of how tolerant your design is to temperature variations.  If this is a one-off that you are just playing with then that's probably as far as you need to go with fault tolerance testing.