If the ramp is steep - by the time the trailer is deep enough to just drive the boat in place, the bow will be over the winch....my wife is in the truck, this is how I do it (takes about 2 mins):
1. Backup the trailer so that the front bunks are just below the water.
2. Pull up the boat till it gets stuck - the front bunks will guide it now.
3. Back the trailer in a bit more - boat will go forward a bit more - until its about 2ft from the winch.
4. Leave the boat in drive (idle - trimmed 1/2 way up) - get the winch connected and start winding it in (this will pull the bow up to the winch).
Note: I have guides at the rear of the trailer - so no chance of the boat going sideways while in gear!!!!!! If you don't, just turn it off at this point - I do it that way too sometimes.
5. At this point I let the trailer in a bit more and wind it all the way up.
6. Shutdown, drive up and you're done.
PS. Use this stuff on the bunks!