I use a small art brush to get the dielectric grease into the pins and sockets in a nice thin coat. That way all surfaces are coated without over-doing it. The stuff is expensive for how little you get, but you actually hardly use any to get the job done.
If the surf looks iffy coming back in, I do pull the finder outside the surf line and put it under the hatch - that leaves the connectors on deck open to get wet if I yard sale - but the expensive finder is safe. I have a container of fresh water in the truck to rinse them down when I load up. I just have pictures in my mind of the kayak getting washed onto the beach upside down, grinding the finder into the sand the whole way in... The worst that can happen is the connection shorts in the surf and the fuse blows protecting the battery - I't hasn't happened yet, but I carry spares of those as well.
Oh - and I also sprung for the protection plan as well
