Actually we welded a new hitch receiver to the trailer tongue, then we can use the hitch pin on both ends for a positive connection between the strap and trailer. You find these 30000# straps at your local farm supply store. DO NOT use the straps rated at 10000# they can and will fail (not a good thing).
Some of our trailers have a mount that lowers the spare tire on a separate hub, I had a special trailer tire mounted to be lowered for the tongue. We have about 50 sailboats on our lake and most of us use the strap method.
To Launch:
Back the trailer to the waters edge. Block the trailer wheels (both sides, all wheels), unhitch the trailer and lower the tongue wheel, hook the strap up on both ends, pull the tow vehicle forward until there is tension on the strap, remove the blocking from the trailer wheels, release the bow cable/strap so the boat can float free. Oh, make sure to hook up dock lines for and aft on the boat and lead these to handlers. Back the trailer into the water until the boat floats free.
Take out is similar to put in but be sure its just a matter of lining up the boat on the trailer. A little practice and its pretty easy.
The power boaters grumble a little since you are hogging the ramp but they get used to it. We only do it at the beginning and end of the season.