I have tried this. It works, but it is a bit of a pain in the butt. Before you back in to retrieve the boat move the winch tower back as far as possible by loosening the bolts and sliding it towards the vehicle and re-tighten the bolts. Then after loading the boat and getting the trailer on level ground you loosen the bolts and slide the tower back into the original position. Sometimes this is all it takes and the bow is tight to the trailer support, sometimes I have had to do a small bump. If you have access to a cordless gun to loosen/tighten the bolts it really goes quickly.
One question, has anyone had good luck with plastic sliders on the bunks? I have always wanted to try that.