From Frankston you could just take Nepean Highway all the way, and preview, in the opposite direction, the route you will take on the Sunday. There are only two major climbs, Olivers Hill just as you come out of Frankston, and Balcombe Hill at the back of Mount Martha, but there are smaller undulations almost the whole way from Frankston to Dromana. And a bike lane! If you want to make sure you've got enough energy in reserve for Sunday, don't ride from Stony Point!
Just ride the bloody thing and enjoy yourself!