I work in St.Mawes during the Summer and have launched works 5.6m RIB down the harbour slip.
It is a very steep slip and the browe is quite sharp! Don't use a Merc as it bottoms out propa jobby!!!
The main road into the village is on average fine (windey, but ok), but there are a couple of narrow places along it to watch out for.
Grove Place in Falmouth by the NMMC is a good place as Kernow says, because you can leave your trailer there and your right next to the pontoon which B&Q Castorama will be berthing.
Im gonna be working (
) so all of you who go, have a wicked time and give Ellen a loud cheer from me!!!