We had the exact same situation last year, same wind same slip. We tried all of the suggestions you have received and more. A few evenings when the dock was deserted we would actually dock and leave about 15 times trying every possible combination.
We finally came up with a solution that worked great and was very simple.
1. Tie a spring line from port midships (stanchion, midships cleat, shroud doesn't matter as it is not going to have much strain). Loop it over a cleat on the dock and up to a rear port cleat or winch. Put the transmission in forward at idle and adjust the helm. This causes the boat to hug the dock even with the wind trying to blow it off. This line is not wrapped on the dock cleat it is just sort of hooked over one horn.
Now release all your normal docking lines and the boat will still hug the dock, you have all the time in the world.
Both of you get on the boat. The next part you can do yourself.
You have to do the next few steps smoothly and you will back out of your slip like a pro.
1. Center rudder
2. Transmission in neutral
3. Flip off spring line. (You can do this from the cockpit as it is not cleated on the dock just hooked.
4. Transmission in reverse with just a little throttle
5. Use your boat hook to push hard against the dock forcing your stern starboard for about 5 seconds. (we had a piling to push against)
6. Reduce throttle if needed and steer out of your slip.
The problem is that when you put the boat in reverse you will prop walk the stern to port, exactly what you don't want.
The hard push with the pole at just the right time completely counter acts that effect and once your boat is cocked so the stern is going the right way you are home free.
It is only 6 steps but the timing is critical but done right you can exit completely by yourself.
Also once you have enough way on put the transmission in neutral and you can steer easier.
And of course if it doesn't work just do a 270 degree turn and try to look bored so everyone thinks you planned it that way.
We also worked out the return process.
