you may also add some extra feed for them ("a feed station")clear a small spot in the middle of the 20 and put up a feeder with corn or some supplemnts,or a feed tray with a top over it.check with you local feed store and see what they have as far as deer feed.build a tray 2' wide and 4' long with a top that sticks out on all sides to keep the rain out.then put somethin like a cornmsweetfeed mix in it.don't put a lot to start with.it may take a while for them to start to eat it.then you can add more and more.

if there is farm land around you,then it will take a while,and you may want to plant some honeysuckle for them to have thick cover.a place to hide and bed may be more what they want.
good luck on whatever you do.