Most of the runners won't be trying to tire themselves out by gallivanting through the parks. At least I try not to. Most runners may be at the parks post race(s) if at all. As a rundisney participant the most I have spent at a park during rundisney weekends is one day and sometimes I have done the race and not gone to the parks at all. You should also note that the Wine & Dine half marathon is not the busiest race. Usually has a smaller number of participants than other races.
Since your final park day is the first day of the marathon weekend I wouldn't worry about crowds. Most of the runners arriving at that time will be visiting the expo to pickup their race packets.