Wow this is a great subject. If I was going to set a property for trophy bucks I would first try to shoot all the old dried up does, their only food takers. Next I would take out all the truly inferior bucks leaving the top bucks to breed. Finally I would crop out enough does to balance the deer/acre hoping to have a three or four to one ratio of does to bucks. There are probably two major reasons for small bucks, not enough food/deer or poor nutrition period. Adding food plots and trimming deer numbers will help. You probably will draw deer in from ajoining properties with the food plots, but maybe a couple of great bucks will come too. It is a tough job you have and without fences you may only have marginal results but whatever you do it should provide fun and in about 3-5 years see some results.
Guys this is a great site to discuss hunting and the great outdoors!!!