ODH; There may be an easier way. You probably don't want to plant all 20 acres as deer forage. Do the clearing on 1 - 2 acres and plant your clover, etc. on that area. In the thick briar areas either cut out or spot spray spot areas with roundup. Plant quick growing trees such as poplars, pines, larches or willows. The trees will eventually grow and shade out the briars. It'll take years for the trees to take over but the briars provide deer cover and you have a percentage planted into deer attracting forage until that point.

Dan O.