Here's a thought. I assume you are talking about pushing the boat in? If so, I'm sure you can get the tires in,,but have trouble getting the winch wheel up. If so, put a second winch on the trailer. Put it further back on the trailer. Once the original makes contact with the lip, winch up the other one, and it will already be over the lip. That might be easier than building a ramp. If it's the trailer tires which are tough, build a ramp, or grind it down.