I agree...I don't see why you'd need faster than 1.8
A lot of people shoot with "only" 2.8 even.
Make sure to bring extra batteries. I highly recommend Energizer Lithium batteries for your flash.
I shot my sister's wedding with one body and my 24-70-so it's definitely doable with not much equipment.
It would have been nice to have a 70-200 on a second body (with a second photographer
)