While fencing might be unnecessary with your pathetic deer populations, the plantings wouldn't necessarily be for feeding the deer in those areas. Those plantings represent variety and create unique edge features and are also good all around deer plants, not just food. I have found deer beds right under mulberries in the past, both at the base of shrub mulberries and at the base of 25' mulberry trees. I also notice deer bedding around high-bush cranberry and especially button bush. The caveat is, as with any small un-established planting of any browseable species, it would need to be protected until it was able to set a good root system and withstand browsing pressure. If you want deer to use those areas year around, diversity is the key, the issue is when planting into those marsh-like conditions, only certain plants will thrive there. Unfortunately, many of those that will survive are also preferred browse. It is a Catch-22 in many respects.