Backcreek, if you only have 4 cleats you could run the spring lines from the mid ship pilings back to the stern cleats. That's providing the cleats are large enough to handle both sets of your 1/2" lines. That would be 2 lines forward, two at the stern and two for spring lines running from the mid pilings back. If you back in, as planned, the stern lines will keep you from getting pushed out into the fairway. The spring lines should be set so they keep you from being pushed aft into the dock. I've used the same set up for years with both a 31' and 36' with zero issues. Both weathered the severe storms that crop up on the bay delivering 40-50kt winds. If a tropical storm is tracking your way you can double up on the lines. Again that's providing your cleats can handle two sets. Check with other boats at your marina. I think you'll get to see what is the standard for your area.