There are two methods for this map, one is eXecutable’s route which involves boosting up a road barrier and jumping on clip brushes here:
Or the slower yet more realistic way of getting across the water found by Windedcone:
Both will save a lot of time, but it’s best to save more time and use a harder strat than lose time using an easier strat.
As for now, I’m not yet sure if you can boost across the water from the house with the angle you get by falling down the clipbrush (my route), but don’t get your hopes down 
Is there some kind of launch we can get from down on the beach?
Don’t think so, but its worth looking around. Only thing that comes to mind now is the broken wooden boat down there. Due to it’s complicated surface it might be possible to Stucklaunch off of it, but it might be very hard/slow in OE.
Fun fact: Stucklaunching was first discovered by ABHing into a wooden boat like this in a mod called Mission Improbable. The main goal was to find a way to skip a water area (but later it has been replaced with a sexy launch).