Your only going to be able to move the boat forward until the lower unit hits the trailer. Which probably not going to give you enough tongue weight.
You can move things around in the boat to help. I would suggest adding weight to the trailer tongue itself, you could hang a steel tube filled with concrete from the tongue.
Actually.. the outboard swings up and will clear the back of the trailer...
But it sounds like the trailer is too long for the boat and the compensation was having the boat transom lined up with back of the bunks then moved the winch post.
If the bunk boards extend aft of the metal trailer frame by more than a few inches you may want to trim off the ends of the bunks when you have the boat far enough forward to put a decent amount of weight on the ball.
A good guide in when the boat is far enough forward:
Put the tongue jack on a bathroom scale, trailer unhooked from the tow vehicle and no boat.
You want MORE weight on the scale with the boat on the trailer. (by Appx 10% of boat + outboard weight)
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You can have an unloaded aluminum trailer frame break with no load in the trailer... just takes a defect crack in the aluminum.