Nice work Rob - it looks like your handy with a varnish
brush as well!
I wouldn't recommend not bothering with masking tape and simply caulking and then sanding
off the excess as some of the other posters have suggested. It won't be too long doing this and all you will be left with is teak
toothpicks and screws.
Masking off is a pain, but it's the only way to do it unless you have the money
to replace your deck
much sooner than you should ever have to.
on my boat is 25 years old and has never been sanded or even scrubbed with a brush (use a mop), and it still has plenty of life in it.
Repair the occasional bad seam or popped bung as they crop up, and you'll be good to go.