While only you can make the decision, it appears that you've given
this a lot of thought already.
Which direction are *you* leaning?
It's fairly common for this list, to purchase "distance only"
sunglasses...but you're right about your correction being fairly
strong, so it may serve you well to have the progressives.
Think about it this way...if you go for a single vision pair, you can
get them for *literally* only a few dollars. You've lost very little
in the attempt, and may find that they work very well for you...or
not. And, your distance prescription is not super-strong, so you
could even use the standard 1.56 index material from most of the
vendors, and hide the edges in a bold plastic frame! Those tend to
look great, when made into sunglasses.
-- Chuck Knight