When we used to take my friend's jet ski out on to the fox river (launching at boy scout island) we had it down to a science. Using an F-450 tow truck (snatch and grab) with backup camera, line it up, drop it in. One person is on the jet ski and gets over to the dock while the truck and trailer are pulled out.
Coming back, keep jet ski running about 50-60' from launch to stay clear of traffic, wait til trailer wheels just start to touch the water, then make a run towards the trailer. Glide it in and as soon as the bow hit the guides, hit the throttle to see how close we could get to the winch. Usually got within 6-12". Get it out, move over, winch the rest of the way and strap it down. Could have it done in about 1-2 minutes. Had a lot of practice, lol.