I use Oreston slip a lot, its fine. Its also just been pressure washed so is clean, free parking, easy fuel within 2 mins. If parking is extremely busy maybe the local Yacht Haven Quay could offer to store the cars etc (Ian Austin would have more leverage on that than me).
Saltash has plenty of space plus two slips within seconds of each other. The Mount batten one is good but it does mean a little more of a trek getting to it by car, passing Oreston in the process
I'm lost on the LOOE front... We could always launch/recover there instead
Peter @ Boatsandoutboards4sale ~ www.BoatsandOutboards4Sale.co.uk
~ 07930 421007