An optional method for you to consider:
Lower the trailer tongue to the ground then support the motor skeg with a block, or wood etc. Remove the mounting bolts, with an assistant helping to balance the motor on its skeg while the trailer tongue is raised slowly. As the trailer tongue is raised up essentially lowering the boat's transom, you can then mount the motor in the new holes where you wanted to. Be sure to re-seal the holes well to avoid water damage.
That 75hp motor should be manageable with 2 people, especially if you're only balancing it on the skeg.
Go fishing