After you grab the spring which you are attaching midships, what happens if you turn your outboard (best) or rudder (second best) so as to move the stern to starboard (like you are turning to port). Then put just enough power on to move the stern to stbd and put the boat parallel to the dock, but not fully stem the current. If you can turn your outboard, you have a stern thruster, something very few of us inboard guys have. Wonder if the spring would then do its job and crab you in while keeping you parallel to the dock.
I find on different boats, depending on the position of the mid ships cleat, different rudder positions and power setting may be required to get the boat to spring in. Some are so poorly placed, you just cannot make it work. But you've got an outboard that pivots (stern thruster!), but you've got difficult wind/current combo.
Hard to know without exactly what will happen without trying in your boat, in your current on your dock. Once you get the 2 lines on, seems the experiment wouldn't cause harm, and if it works you could possibly eliminate the bow line. If it works your bow line would go slack, and she'd crab in with tension on the spring.
When I had a 52 sometimes I would use a winch to handle a dock line, and found it very helpful. Have to be careful everything run fair, and you don't take out your lifelines, but nothing wrong with using winches IMHO.