Re: Your trailer is in line, not your boat!
Ever seen a tournament launch? One after another, they back down, tap the brakes and let the unoccupied boat float out into the no wake zone. Every 6th boat or so, 5 or 6 guys step onto the deck for a lift out to their ride.
As an avid bass fisherman, and occasional tourny fisherman, I have yet to see that method. Generally what I see is one guy in the boat, and the other backing him in, with the same tap breaks and float off method. If the nonboater is truly a nonboater, and not just a back seater, he will usually just take it to the dock with the trolling motor, and the boater backs in. If it is a 1 man per boat tourney, for the most part two guys will team up - 1 backs in, and one is in the boat. Then, he docks or beaches and backs the other guy in, and between them, 3 or 4 more have launched.
I refuse to unhook the winch strap before backing in if the ramp is more than 1 trailer length long (most around here are). So, I ride down on the bow deck, and the driver stops when the wheels are at the waters edge. Then, I reach over the bow and unhook the winch, and the driver backs the rest of the way in, with the tap brakes and float off method.
On the chance that there is a courtesy dock, I use a slightly different method. Because there usually are obstructions (boat tied to end of dock if it is long, or seawall paralleling ramp or such) I walk down to the dock, and stand in the middle, about 1 trailer length from the waters edge. When the trailer gets down there, the driver still stops at the waters edge, and I unhook. But, I grab the bow line, and walk down the dock at the speed the driver backs in. The boat floats off, and the momentum keeps it going to the end of the dock, where I proceed to hop in, start the motor, and idle out of the way.
For loading, I powerload (never much more than idle - I tell the driver the sweet spot of the trailer). I am able to run up on the trailer, and end up right at the bow stop, or about 6 inches from it. I kill the motor, jump in the bow, hook up the winch strap, and wave to the driver to pull out.
I have found the previous methods to be the absolute quickest, yet safe, methods to put in/pull out my particular boats. I always design my trailers to best suite these methods as well.