For a lot of years, I've had similar problems. Now I've copied this example accurately;
Apart from substituting his warn 4500 for a superwinch terra 4500. There is far more power than is needed.
I've used Wichards on both shackles.
The remote means connecting the line while pulling it tight on to the boat with the other hand (this is enough even in quite strong cross winds to keep the hull in line. as soon as the line/winch takes the load, the whole rigs straightens on the rollers.
single handed in most conditions (keep some perspective here) is simple..
From a safety point of view, it betters the standard system we all use in a significant way; if you watch cars pulling heavy ribs up slips it's nearly always only the winch strap holding the hull on the trailer, this always looks a little iffy to me, with this new setup, there is much less chance of the initial inertia causing a boat to depart from the trailer...
I think (and I've done it many times) Using the engine at the point of recovery is full of potential issues....this system means it's off as soon as you hook on. It all works better if you keep it a little shallower,power is no longer an issue and your bearings will last longer.