I have a small fiberglass boat that is just under 14'. I also have keel rollers on my trailer, as well as bunks. The keel rollers will allow the boat to roll right off the trailer quite easily even on level ground. This means my launch/load procedure go something like this;

Prep the boat and back the trailer down into the water with winch strap still attached. I hook a long 30' line to the bow eye and unhook the winch and shove her off. She floats clear of the trailer and I pull her over to an out of the way spot and tie her off. Park and go fishing.

Loading is about the opposite, I shove the boat off the shore and towards the back of the submerged trailer. I use the line to pull her up on the rollers and up to the bow eye and hook the winch on.

Now, on steep ramps, this is a breeze. On shallow ramps, I have to drive her up. Once up I leave the motor in gear (a tiller steer) and set the steering drag level (Nissan motor, has a lever that allows me to control the steering friction, sorta like drag on a reel) to max and with it in gear, walk up and hook the winch up. I kill the motor and climb out, looking something like a beached walrus doing so.